My worst expectations on cryptocurrencies are directly related to my bad investmrnts in cryptocurrencies. On of my worst investments is in sparkster, i regret investing in that project, i invested $1k worth of ethereuem in it in 2018 and that investment is worth less than $20 today with no liquidity and no hope of returns  this ranks as one of the biggest investment mistakes i have made.
I believe it is always good to make good research before investing and don't follow the hype.