A skilled engineer who focuses solely on engineering will produce much better work than a skilled engineer that also has to focus on /marketing /sales /investors /accounting /facilities /IT /management /HR
Either a small fish in a big pond or a big fish in a small pond.
Edit: Also consider that you may be a person that can produce a lot of value specialized, but practically no value when juggling all the above items. You'll find that if you can produce a lot of value at any level then you can negotiate from a position of power.