I'm not sure what other people will recommend, but I don't personally feel that you need such a deep knowledge of fundamentals to be a good technical co-founder. More important is your ability to pick things up when you need to.
You don't need to be a decent DBA, a pen tester and a network admin to get your startup off the ground. You need to be able to wear all the hats, but by the time you actually need a master of each skill you'll have the revenue to employ them.
That said, these two paths may actually converge. If you're interested in learning and read a wide range of authors and topics, you'll probably be good at JIT learning stuff when you need to change hats.
You don't need to be a decent DBA, a pen tester and a network admin to get your startup off the ground. You need to be able to wear all the hats, but by the time you actually need a master of each skill you'll have the revenue to employ them.
That said, these two paths may actually converge. If you're interested in learning and read a wide range of authors and topics, you'll probably be good at JIT learning stuff when you need to change hats.