A ponzi scheme is defined by the fact that the only profit to be made comes from people who buy in after you. If companies don't return capital to the markets (through dividends or buybacks), then it absolutely fits the definition of ponzi scheme.

The proper cycle of a publicly traded company is that it trades equity for capital, uses said capital to invest in itself, then returns capital when it reaches a certain maturity. Anything else is a scam.

Or the company is bought out for cash, as in the case of Dell, or bought by another company for cash and/or shares.

No company goes public with the intention of being bought out.

And the entity that's buying the company does so with the intention of distributing the profits (to themselves).

The difference between a company and a Ponzi scheme is that the company is actually creating some value. It is converting capital into resources, priorities and processes that generate more capital than it gets. At some point it can't convert capital into more capital, so it's better to pay a dividend -- but even if it never does this, it's not a Ponzi scheme if value is being created.

A Ponzi scheme never generates more cash than it gets -- it only simulates profits.

But shares are traded because there's an assumption that the company will distribute earnings (as dividends or buybacks) eventually. Otherwise they would have little (voting rights?) or no value.

Dividends are far from the only way you can realize value as a buy-and-hold investor with infinite patience. For example, the company might be acquired in a cash-for-stock deal. (I don't hold my Microsoft shares in the hopes that someday Google or Apple will just swallow them for old time's sake, but hey, stranger things will happen as time goes to infinity.)

This means that even if your stock of choice never distributes dividends, it is essentially a non-expiring call option on participation in an eventual sale.

Getting into a Ponzi scheme late is okay, so long as you still get out early (before it becomes apparent that it is a Ponzi scheme).