Do what's best for you. The company has no loyalty to you - if they decided tomorrow that you were no longer useful to them, they'd fire you without any hesita

Do what's best for you. The company has no loyalty to you - if they decided tomorrow that you were no longer useful to them, they'd fire you without any hesitation or warning. (I've seen it happen to a lot of people.) Thus, there's no reason to feel that you should have loyalty to the company. People moving on to different jobs happens all the time. They get better offers, their needs change, they burn out, etc. If your company is run rationally, it should be able to deal with people leaving. If not, it's not your problem. As you noted, even a cofounder of your company has left already.