I agree.
ISA is a cash cow for sure.
1. You pay for yearly membership
2. You pay yearly chapter dues
3. You pay for testing, certification, and recertification
4. You pay for some CEUS though many are free.
5. You pay for events
6. Some are crazy enough to pay to compete in ISA climbing competitions.
But for some reason I've continued to do it for the last 10 years! BCMA is a nice feather in the cap I suppose. For me it was a personal goal that did help me expand my knowledge base. You're right though, I'm not sure how much more work it will lead to compared to just being a certified arborist. Most of the people in my area are just looking to hire a good, affordable "tree guy."
Another goal of mine is to have two of my employees become certified arborists so I can tell customers there is a certified arborist on every job site.