Very different situations there mate.
Stones and Lukaku were hugely sought after players who were first choice for Everton and earned themselves moves to clubs in the Champions League who we forced to pay huge amounts for at the time. Any efforts to keep them were futile because the clubs coming in for them had huge pulling power.
Lookman is different. He's not an established first team player, he's never been happy since he got here, and there isn't a queue of bigger clubs lining up for him. He's absolutely desperate to play first team football seemingly, and he's obviously already had a great experience at the very club that have come in for him. They're not a bigger club really, and can't outmuscle us financially, but the player is dead set on leaving and it isn't healthy for him or the club to keep him. Added to which we can't promise him first team football because we've just spend £35m on a player who plays in his position.
This has nothing to do with the ambition of Everton. It's a simple case of a player desperately wanting guaranteed first team football and for some reason not liking the lifestyle he has in Liverpool.
Why on earth would that set any alarm bells ringing?
