Corporate culture is based on constant growth and ever increasing profit margins. Eventually they’ll amass so much of the wealth that most of the lower class won’t be able to purchase anything other than essentials like food.
No new cars, no tech gadgets, no fancy dinners, no vacations, no disposable income.
When we get there the economy collapses because there’s no money going into it.
The profits stop rolling in, unnecessary goods stop being produced, and the luxury goods producer’s shut down.
At this point the money they worked so hard to hoard becomes worthless because they can’t buy anything with it.
What’s the endgame for them if their current path takes them to a point where their assets are more or less worthless?
I don’t think you can think of it as some sort of logical plan. It’s a bug, not a feature, of capitalism. What you are describing is the inevitable end of a completely free market with no regulation. The strong (economically) keep taking from the weak until we have the situation you are describing. From there the next step is dependent upon whether the weak form a cohesive identity and seize power (revolution) or stay fractured around smaller identity cleavages (race, religion, gender, etc) and are subjugated.
It’s tragedy of the commons on a supermassive scale. No one comes out on top in the end, the overprivileged just take a little longer to die. But die they will.