My doubth is to validate a transaction you need knowledge right?... how come people who have more crypto money stake get more power to validate transaction, don't you need technical knowledge.

Yes, there is less need for tech knowledge to participate in a proof-of-stake network valitadion, wich is good, because that means it is possible to have more nodes to process transactions (more decentralization)

When BTC was early, people used to solve this mathematical equation to validate transaction, miners, but when this ASIC chip stuff came computing power became important for validating transaction stuff. That sucked and sucks still I guess.

It is still the same. Computing power was always what was needed, but the ASICs machines are specialized to do the calculations needed to mine a transaction. They arent useful for anything else. They actually made mining more efficient, wich as a side effect, increased the computational power needed to valitade a transaction.