I hope this isn’t violating some forum rule: if so, sorry, and a mod can delete it.
I have no association at all with Blender except as a user of it, but I think a lot of us are using it to create game content, and it’s a very powerful tool provided absolutely for free to the worldwide community. In fact, if you’re on Linux it comes right with your operating system!
It’s totally optional to donate to their foundation, but if you use it and want to help them out to keep providing good open source stuff, I think it’s a nice thing to shoot them a couple dollars/euros/yen/rubles. Even if you can only afford a small amount, I think they appreciate that, since most people will never give them anything.
If in a few years of work I can ever get a game to a saleable state, I plan to donate a % of the profits to the free tools like Blender in addition to the UE4 license %. Good to give back, I figure.