Generally they don't, they compensate part of game price with cards, consider it extra discount.

Apart from extra cheap games on sales and free giveaways, then it can be pure profit.

Of course, it's not cryptomining
http://psteamcommunity.yuanyoumao.com/tradingcards/faq
Is there a limit to how many trading cards can drop?
Most games will drop a number of cards equal to about half the number of cards in that game's set of cards.

no. 50 cards is few ,not a lot at all, the chance is 1%

引用自 Nakedwildman：

引用自 Ryuu：

You don't have other unplayed paid games.
Make screenshot of badge page, pretty sure there are no drops left.

http://prntscr.com/hvmru1

on some it says "no more card drops available" but for example miscreated does have them aswell and they dont show up

No, it's doesn't - 87 hours played. It's just you got 1 foil card.

You don't have other unplayed paid games.
Make screenshot of badge page, pretty sure there are no drops left.

And why do you expect more?
http://psteamcommunity.yuanyoumao.com/tradingcards/faq

引用自 Northern3：

引用自 Ryuu：

You're level 0, limited accounts don't get drops, spend $10.
Absconding Zatwor was deleted from Steam store, you can get cards, but they won't be marketable likely.

does gifted games works or sharing games from library

No. See FAQ.

You're level 0, limited accounts don't get drops, spend $10.
Absconding Zatwor was deleted from Steam store, you can get cards, but they won't be marketable likely.

yas, that IS the point

http://psteamcommunity.yuanyoumao.com/tradingcards/faq