He is 21 and has half a season of top flight football where he was decent but not extraordinary. In any case, he is not a Saka or Greenwood level player where you have to keep him at all costs.
His story has played out at Arsenal many times, where fans get excited about a 20-21 year old playing decent football and don't sell when their value is high. Coquelin, Gibbs, Ox, Coquelin, Wilshere, Walcott, Bendtner; the list is very long.
All driven by emotion and not rational thinking.
Kai Havertz at the same age as ESR went for 70m and he had played more than 100 top flight games and for Germany.
ESR for 50/60m would be a complete ripoff.