Walk Away or Stick it Out: Need Perspectives

48, $15M net worth. ~$12M is liquid.  $2.5-3M W2 Income per year. MCOL area. Spouse and 3 kids (1 in college 2 in H.S.). 

My dilemma:  I have been with my current company 10+ years. Nothing wrong, but I am growing bored and not applying myself fully.  Feels like I need a new challenge.  I want to work, but not in a full time corporate role.  I want more flexibility and freedom. Less pay is ok.

Probably need $325k per year to maintain our current lifestyle.

No real debt other than house and rental property.   

Can I walk away? Should I stick it out a few more years to get NW closer to $20M? 
Sometimes feels crazy/risky to leave as so many would kill to be in my position.