It's not about making people suffer. Eich used his wealth to lobby for something that many people find objectionable. Mozilla is quite an ideological company (many who work there are probably somewhat driven by the "mission" rather than necessarily the company's financial performance), and so the CEO publicly supporting criminalising same-sex marriage could affect hiring and staff morale.

It's not like his career has been destroyed. He's still incredibly wealthy, and has a new browser company. People can use that, and work there, if they want.