I bear no resentment towards Saints fans, and I only drink their tears being fully mindful of the pain I regularly suffer as an Evertonian.
But, in all honesty, it must come down to 'ambition' - I obviously believe Everton are a historically bigger club by all measures, but I think Koeman's decision to come here (if it is indeed true, because if not then I am a mug) comes down to the project he has been offered; and Southampton's owners are considerably richer than Moshiri, so must be capable of matching it, no?
Feed the fume.