Success is predominantly underpinned by a strong management / coaching team, and a prudent / canny owner (or a rich one). If those foundational elements are right, then it ultimately enables the team to invest in the playing squad over time and improve performances (within a particular system).
So, ultimately, I think the coaching set up is the most critical, particularly when you look at recent success stories from Champ to PL:
Sunderland: Regis Le Bris
Forest: Steve Cooper
Then the teams that are overachieving after a management change:
Villa: Unai Emery
Palace: Oliver Glasner
Everton: Moyes
Our greatest investments were always Robins and Viveash (+ Lawrence) and now Lampard and Edwards.
We should give them whatever we can afford - or even a bit beyond that, to be realistically competitive - and trust it to them.
Over time, I think that will prove to be our most successful strategy; whether we survive in the Premier League, become a YoYo club, or settle into life as an established / top Championship club.
If we get bought by a Billionaire, then we can shoot a bit higher. If we don’t, then we can’t, and that’s fine with me too.