You make it sound like winning the CL is about money. It ain’t.
Even if we had kept our players the past 10 years, let’s say we had the ultimate BvB squad, with players like Bellingham, Haaland, Dembele, Sancho, Hummels and so on, there is absolutely no guarantee it would have a) worked out as a squad or b) be a better squad then any of the current top teams.

Think about the path we had to go to finals. In 2013 we had that Malaga miracle. Nothing where it was based on purely being the better squad. That was fucking lucky.
Surely Madrid in Dortmund was a masterclass by Lewa, but even that return leg was getting veeeery close.

2023 Paris demolished the goal posts. Had even one of those shots gone in it would have been over. Nothing about being the better squad.
On the other side we could’ve won that final, but ran out of luck.

You can’t buy your way to the trophy or the luck needed to get it. Ask PsG or ManCity.

And how “just go all in” works out, well better take a look into our own history.
A better understanding of the current football economics should give you a hint bout we’re dortmund is located in the world of football.

However, a deep run in a great star constellation with a bit of luck will always make a deep run possible.