if you have to suggest someone who just started and can only do one or the other will you suggest to build some more seats or live with less income while he trains?
I already explained that I personally invested in trainees and a trainer while spending lightly on arena, then prioritized arena above everything after that. That is why I am telling you the argument has never been "spend 100% of your income on arena".
I didn't choose the number randomly. With a 7 million investment you can build a better 20k arena than most 20k arenas...so if your trainees and players are worth 8 millions on the market you can turn them into a 1 million roster and 15k seats.
If the new player in question can guarantee they can make 8 million off their trainees, that 'would' be an option. They don't hand out multimillion dollar trainees for free, and they are so valuable for a reason. You'll never replace the trainees you sold off so you're essentually starting from the bottom again. You replace trainees with 32 year old plus players because you only have 1 million of the 8 million left, meaning your roster will significantly decease in value over the course of a season.
Assuming you spent 4 seasons to get your trainees to that level, I'll have the 15000 seats by then doing it my way, with keeping my trainees, with a winning record. I'll probably have the million in cash as well. If I sold my trainees next season (which I won't), I'll have the 7 million you would spend on catching up to my arena to spend on players.