Not only that, liverpool were willing to make him one of their highest earnest even above the likes of coutinho at the time and he was only 20 that's how highly they rated him. Imo he should also be amongst the highest earnest maybe not on de-bruyne, silva or even aguero level as they've done it on a more consistent basis but he should definitely be closer amongst that group in pay. People are forgetting he had a very good first season under pep even though he tailed off a bit towards the end he finished it with 10 goals and 21 assists(incl. pens won) and was even voted second on the POTS awards on this forum. He carried that natural progression onto last season where he had his best ever season with 23 goals and 17 assists and was voted 3rd best only to silva and de-bruyne in a record setting campaign and a case can even be made for him being 2nd on that list.
So this is a player whom for the past 2 seasons has been at least a top 3 performer for the team and is still just 23. We are not talking about a bit part player here but an established key player who still has years of development ahead of him. From some of his numbers last season(graph below) you can see he is on the cusp of something special once he gains composure in that final part of his game and could be looking at salah level numbers that's how scary his prospect is and both him and his team knows that as well as pep as he's said so himself. Obviously no one is above the club and if his demands are ridiculous then better to move him on. Arguments on whether he deserves to be paid de-bruyne, silva money is another case but he certainly deserves to be talked amongst the most important to the team going forward based on what he's done the past 2 seasons and I don't begrudge him or his team for thinking so.