Ask HN: Is an early exit strategy a bad sign?

I recently talked to a founder who wanted me to join.

He doesn't seem to have any concrete prototype yet. And it's hard for me to conclude that he is familiar with the tech his company wants to explore. But he said he is confident the company will be sold to other companies in less than 2 years.

Is this something I should be cautious about? I seemed to read somewhere, a startup planning an early sell is not a sincere business?