i've been doing a lot of reading about DeFi's lately, but i can't seem to wrap my head around rewards and where do they come from?
For most of them, the rewards come out of nowhere for doing nothing. You get about 5-10% per year and the coins lose about 40-60% of their value year by year. Not a good deal if you ask me.
There are yet no really good PoS coins, as PoS has not yet been tested in real large scale projects. The first attempt will be ethereum, but it is very late.
There is a very good FAQ about ethereum casper here:
https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQIt is important to notice that staking is a service. Similar to mine, where you put your processing power at stake, betting that those transactions are valid. If the transactions are invalid, you just lost your processing power as your chain will not be accepted.
The same thing goes with pos, as owners are literaterally staking their coins and "betting" that those transaction in a block are valid. If any of them is false, they lose their coins. The coins are at stake, this is why it is called Proof of Stake.