Is buying PS5 games digitally from Others is Safe?

I have recently bought PS5 and I was trying to buy new games ...as we all know new games cost us very much...so I was checking in OLX for used Discs in 2nd hand ...I found lots of people are selling the games online itself....like they will provide their PS5 account and we can download the games from their account to our account (not sure how can we do) and they charge it game wise ...is it safe ? Even if we buy from them can we play normally like we buy from playstation store or disc?