What exactly am I risking if I buy Steam keys from unauthorized sellers online?

I own a legit Steam version of Don't Starve Together, and I want to play with my friends. However, they play a pirated version, because they cannot afford (or don't want to pay) the price of $15 (they said it costs that much) per 2 copies. I want to play with them, but neither do I want to gift them a $7.5 copy each, nor play a pirated version.

I plan to visit some trading web-site and buy a bunch of Don't Starve Together keys that cost just a few cents and send to my friends. However, I have read that I will risk:

1. Getting nothing and just wasting my money (I have chargebacks for that)
2. Getting banned on Steam (this is something I really don't want, for obvious reasons).

Is it actually possible to lose my account if I buy games in such a way?

I tried to google for it, but I didn't see any valid source, or any official answer from Steam about that: only "u gonna get banned" or "you will get scammed 100% stolen keys" with no backup.

Solution 1:

You can definitely get stiffed (receiving nothing for your money), or also get your account suspended or banned. Steam has a page in their knowledge base about this includes:

Piracy or Hacking

This includes using an unauthorized ("hacked") Steam client to access Steam, attempting to register fake CD Keys or attempting to register a CD Key which has been published on the internet.

Payment Fraud

Any fraudulent credit card use, credit card chargebacks, or Paypal chargebacks (regardless of when the transaction occurred).

Redeeming Fraudulent Gifts

Never accept a gift from an unknown user. Any accounts tied to a redeemed gift from a fraudulent source may be suspended.

In short, yes you can get in trouble with Steam for doing this -- in my opinion it's worth the $15 to buy them a 2-pack rather than risk the possible account issues. Your thoughts may differ, but it's definitely a risky action to use an unknown/unofficial source for game keys.