Mane was a top player he cost 36 mil fella. He was wanted by all the top clubs and yes mainly on potential but how is that any different to most footballers.Not a top top player doesn't mean not that good,Mane wasn't a top top player,or Salah,or Robertson,you see you don't to spunk money everywhere.
In the same season Sane cost ManCity 37 mil Kante only cost Chelsea 32 mil from Leicester and he was a recent EPL title winner. Only Stones and Pogba cost more than 40 mil at that time and we all know what happened to the market once those deals happened.
Salah cost big money for us at the time he was signed also so just cos big money for us now will be in the 70 to 100 mil mark does not make it any different to 36 mil when we signed Mane. We will not always be able to find a bargain like Robertson and as everyone keeps saying 75 mil for Van Dijk looks like a bargain now.