And vice-versa. The better your corporate facilities (VIP boxes, function suites, etc), the better clientele they will attract (investors, businessmen), the better investors they attract the more likely that your fat-cat chairmen will upgrade them (without notifying you, afterall money-making is their territory.)
I'm not entirely sure of the game-mechanics behind them, but generally it is prestige that attracts rich people, because as someone already mentioned above "they don't come for the football". So I imagine that signing players more prestigious than your club is used to or having a visiting team from a higher league or another nation are where corporate facilities pay off best by attracting big-spenders.
I hate to be dumb but what exactly is corporate facilities?
Is it just the boxes you get in large stadiums?
Basically yes, but in some of the bigger stadiums IRL they also include conference centres and meeting rooms for vanity purposes (e.g. "We've had our board meeting at the Emirates this month", "Yeah, well we've had ours at the Nou Camp")