Assuming $5000 w/first service then $1700 to ride 5000 miles isn't outrageous if it was fun. People spend more than that for a two week vacation out of the country (or even in the country). Harley's rent for about $150 a day where I live.
So what was the deal breaker? Moved up or just fell out of love?
Riding is a crazy hobby and sometimes, out of nowhere, people just dont think its worth the risks. He either reached that point, needs cash, or is upgrading. Whatever the case, you know you'll never forget those 5k miles. Good luck.