Don't underestimate the gap between what is foolish for a company and what is foolish for an individual employee at an enterprise IT department.
I think that IT staff of large enterprises are not foolish when they cling on to overpriced Oracle installations as that creates job security and high wages for them even if they are mediocre (not all of them are mediocre of course)
Also, it may not be foolish for a large enterprise that runs on Oracle to keep doing so, because any benefits from switching could be dwarfed by the cost and risk of switching.
But I think there are a lot of medium sized companies outside the tech sector for whom a decision to go with Oracle is foolish and not switching is foolish too. They're not just overpaying for Oracle licenses but also for DBAs, and they are creating a stagnant IT culture that is less likely to come up with innovative solutions for new business problems.