If you don’t ask—the answer is always “no.” No one likes to be rejected. Asking professional people and successful authors for an endorsement can be emotionally risky. You better learn how to deal with rejection. But if you don’t ask for the support, you’ll probably never get it. No one called me and offered to write an endorsement; I called them. You’d be surprised to know who I asked.
You know what you want. ASK for it. All anyone can say is NO. But what if they say... YES?