How do users who give gifts afford them?

I gave some gifts on my account from bundle games I don't need: I buy a bundle, keep some games, trade others, and gift others. But I see a lot of gifters who are on level 10, with the total amount of given gifts that totals to tens of thousands of dollars, but how is this possible?

First of all the total amount of gifts sent is less than that because SteamGifts consider the original price, which is most likely never paid, but still even at 50% of the original price the amount is high.

Also there are developers/publishers who does this as a promotion for their site, but not everybody.

Speaking for myself, I have a job, not that high salary, enough for the house and some savings. If/when I buy a game, I buy it for myself, I will never ever buy Fallout 4 and give it to completely strangers just to increase my level to win more games later. If I want to cash out some money to strangers, I prefer giving it to charity to provide food/water for the poor or world causes, which I do very frequently. That's why I like HumbleBundle because I can change the splits and give nearly all to charity.

Maybe somebody likes to spend their money for others? if so please explain.