Projects like plasma are offering a 30% APY yield in their platforms.

You might ask where they are getting all the money to reward stakers?
Well in a good $XPL drops by 5% in a worse day 15%.
That means you lose 30% in 3 days.
That is what the rewards cover in 1 year.
Just like that you will be their exit liquidity.
By the time one year ends you will be down 98% on your initial investment.
It's a good business model for them but it's slowly killing DEFI.