It's a ridiculous analogy for sure. The player wants to leave to a more successful club, that's all there is to it. It's unfortunate, but these things happen. Not all players want to stay at their home club when presented with a better career move. It happened before with the Michael Owen transfer. Also with Beckham to a lesser degree.
Liverpool fans are angry because they hoped Arnold would prioritize Liverpool over any other club but he seems to have other plans and higher ambitions than just becoming a Liverpool legend. Of course, the move is polarizing because Liverpool look to establish a dominance, but we don't know if they actually do it or how much it lasts.
People have to understand that not long ago, even under the great Klopp, Liverpool even failed to make CL places and had to settle for Europa League football. That's not very good for a player that has high individual ambitions. To went from playing a CL final to not even qualifying in a span of 2 seasons. Very inconsistent.
A bigger club who is offering more money.
It isn't like Liverpool are proving themselves loyal either, they have shipped Mane & Firmino the moment they have declined, they are low balling Salah for the 2nd time of contract renewal negotiations, despite being the best Liverpool player in this century in term of level, and they have just started negotiating with VVD despite being a transformative player for them. They have already brought Alison replacement and are ready for moving on from him.
And their fans cherished everyone of those moves, because it is shrewd business.
But when it is business as usual from the club part, every player has the right to treat this as a business decision rather than being gaslighted into loyalty argument.
This is last year where Trent will get an upper hand in negotiation, his next contract will end when he is almost 32, and in Liverpool he will likely be thrown away after this one. He has every write to move for bigger club who has more success and offering far more money.
Like seriously, the rumoured difference in salary is about 30M in his entire contract.