I do not think that loyalty requires you to take less money. Consider how much money Messi has earned Barcelona so far, without Messi ever playing for Barcelona they wouldn't be near what they have been in the past 15 years, that dude made them a great team. Don't get me wrong Barcelona was a good team even before Messi, they have been a good team for decades, but they were not a team that was at the top of the list for 10 years in a row before him, that is a rare thing to do, and that is why him getting paid even if he doesn't provide as much anymore is a thing.
I remember Kobe Bryant getting paid 25+ million (which at the time was a big number, nowadays not so much) even during his injury years and even getting that extra cash on his last year as well, he didn't provide anything at all for 4 years, 3 years injury plus one year retirement tour, but he still got paid, why? Not because who he is, but because what he did for the team before.
It's not just about money at the same time, but only about money. You can talk about the loyalty of the player to the club and the club to the player, but there are all sorts of financial rules that need to be respected and followed so as not to have unpleasant consequences later, and I'm not sure that Messi and Barcelona want the liquidation and bankruptcy of the club as a thank you to the player for his career
It is because of them that the contract is still not signed and from July 1, Messi is officially no longer a Barcelona player and will have the status of a free agent, despite the fact that Barcelona president Joan Laporta does not formally allow this by all means. But the series continues, despite the failure of all deadlines.