Both
Basically, I think Sainté would have signed for half that offer.
Malcuit is a former winger, from Monaco's academy IIRC. He was a quick guy who dazed for short stretches because of that explosiveness.
Couldn't cut it in L1 though because he lacked other offensive weapons, including offensive IQ. Full effort guy, no doubt, and big speed, but that was about it.
So he moved to L2 and at some point was played as RB (and I think I saw him at LB sometimes).
His qualities are clearly a better fit there and he's been good with St Etienne since coming back to L1 (but has only started this year). But I'm still far from convinced he's good enough to face good wingers. St Etienne is a defensive team and he looks better than he is because of the system IMO.
So basically you're signing a 25 year old who has 6 months of L1 experience at RB.
Signing a RB for that much money is questionnable, but given the context is IS insanity.
I'm not sure if Corchia would join West Ham (he has big suitors for years, but hasn't signed anywhere), but he's a much more proven commodity and probably available for the same price.