You have less to lose than you think.  You have more to gain than you can imagine, even if it fails.

We tend to over-scrutinize action, change, and unknowns, and under-scrutinize our current situation.  Most change happens at the margin anyway.  How precious are those marginal perceived benefits of known mediocrity versus the marginal risks of unknown potential greatness?

It’s not about the great feeling of reaching the summit.  That won’t be as great as you think.  It’s about the new summits that come into view when you get there.