There's a simple solution: employees shouldn't accept a lower-than-market salary. Having been in this situation myself I understand that the psychology of these

There's a simple solution: employees shouldn't accept a lower-than-market salary. Having been in this situation myself I understand that the psychology of these situations makes it difficult for early employees to maintain an employer-employee distance from the founders, but (in my experience) that spirit of camaraderie ends with the acquisition. The founders will likely be gone within a year, the unique cultural aspects of the company will be subsumed by the acquirer, and early employees will be stuck with nothing in exactly the kind of company they were avoiding when they took a startup job.