How much cash should I save for my investment warchest. Is 100k enough?

Enough is subjective. You'd have to ask yourself: enough for what? What is your investment objective/goal? If it is to get a passive income of, say, $4000 monthly, then no, 100k is not enough.

It depends on factors like

1. What is enough for you?

2. Your expected returns p.a or total returns are within reasonable amounts that is relatable to the capital and time horison to the skills

3. Is it an amount you are willing to lose up to 50% and still be able to hold your market position incase of a market crash/correction?

p.s 50% is a guage of possibilities of the market conditions not that it will happen

enough is subjective to ones needs and goals. Hope this helps you:)