Blizzard
In 2010, I went to a site that was being advertised in the game regarding an epic mount, not to get it, but rather to report the site as a phishing site, as I was aware the site was being used to steal World of Warcraft accounts. In doing so, the webmaster of that site was able to pull my login details from memory (expecting there would be some login prompt to steal that information, not expecting malicious software to be on it that was capable of pulling sensitive details off of your computer), I know this is how my account originally got compromised as I got logged out of World of Warcraft directly after I went to the site to report it (even going as far as attempting to block scripts on the site that were expected to be malicious, it wasn't enough to stop it from happening regardless). So in my effort to prevent others from become a victim of cyber criminals like this, I in turn ended up becoming a victim of it.
Probably within the same day of going to that site (earlier in the day), I had canceled my World of Warcraft subscription because I wasn't happy with the pre-release event for Wrath of the Lich King, was expecting I would go back to it later, it wasn't until I attempted to go back several months later that I found out I couldn't access my account. I had been receiving emails during this hiatus of the game stating that my account had been banned for gold sales activity, expecting they were attempts to steal my account, so I chose to ignore them (similar to the theft attempts I was getting targeted at my Runecraft account over a decade ago). Fact of the matter is at least a small portion of those emails I was receiving were factual & ended up in the accounts actually getting banned for the thief's activity.
When I contacted Blizzard about this, they agreed that it looked like my account had been compromised & they returned it to me, but I still had to get it unbanned to be able to use it again, stating I had to fill out a form to get the reactivation of the account finalized. The problem is the core account was not in my name, it was a store account from a LAN center that I was volunteering at as a Computer Technician & I wanted to get in to the game as quickly as possible so that account was given to me seeing as it wasn't never used (adding the expansion packs & taking over the subscription fees when I acquired it that day). Acquiring the core account through this method was a mistake, seeing as this resulted in only being re-victimized by Blizzard seeing as I couldn't confirm ownership of the account due to it being the name of the owner of the LAN Center on the account. When I asked Blizzard support what I was supposed to do with the account if they wouldn't unban it, they bluntly stated, "Repurchase the game." My response to that was, "Not happening." I have not made a single purchase of a Blizzard product since that day in 2010, it is now 2019; while I did have an interest in Overwatch when I was watching a stream on Twitch, I quickly lost interest when I found that the publisher was Blizzard. Aside from Blizzard products alone, I wouldn't put my money towards anything that was either being promoted by Blizzard (like the Mt. Dew promotion of one of their expansion packs) or any other media, merchandise or products under a Blizzard franchise (this meant there was no way I was going to be paying to go to a Blizzard movie either.
Around 2014, I became aware that Activision had a parent company that was a combination of the 2 & as a result, I stopped purchasing anything under Activision also. The reasoning behind this was that any purchase I made towards an Activision product would still go to Blizzard through the parent company, so based on the stonewalling & revictimization back in 2010, Activision got included in this boycott through their parent company.
I may still play the games that I own (older games, mostly offline), but I won't put any more money into these companies unless I at least get back what I was ripped off for on my World of Warcraft account; the game data doesn't really matter, I'm known for starting over regularly anyways, but I lost over $1000 on expansion pack purchased & subscription fees, I needed to at least get back the core game & the expansion packs I had put towards the game before I would be willing to purchase from Blizzard again. At least this used to be the case, seeing as I can no longer afford the subscription fees so at this point any gift towards getting back what was stolen from me when Blizzard decided to take the revictimization approach would likely be rejected (at least until I had the funds to be able to pay the subscription fees again), so this is likely a boycott that will never end even if a friend were to attempt to get me back into the game by purchasing the core game & expansion packs that were stolen from me when the account was banned over a cyber criminal's actions (only way I could see out of that would be if that friend were paying the subscription fees, which I don't really see happening unless they are really insistent in getting me back into the game.
While I was working for a third-party gaming company (messenger that was designed for PC gaming, adding functions like in-game chat, screenshots, video recording, streaming to online streaming services, time tracking, etc.), they favored Blizzard & seeing as I was the head of Game Support, I was forced to have World of Warcraft on my PC to make sure it worked (tested through the company account seeing as I no longer had access to it through my own), which literally made me ill... I did protest this at first, however seeing as World of Warcraft had the top spot in our game ranking boards (later getting taken over by League of Legends), I didn't really have a choice if I still wanted to have that position in the company (or a position with them at all when you get right down to it). Point is if I could have let game fall off of the charts by not updating the definitions for it, I would have allowed it to happen, so long as I never had to touch it again (of course it would have been picked back up again by whoever took my place when I left the company). As it is now, I avoid any product that has to do with Blizzard, even avoiding a good number of giveaways that have been offered over the years over their Battle.Net platform (and Blizzard launcher; luckily I don't have to worry about purchasing their shit over Steam because they don't have anything listed there). If there was ever a company to chase of their customers, Blizzard would be in the top 10 (using this number because I've run into roughly 10 that have done nearly the same thing, also currently being boycotted for that reason).