Lol, I had my S5 for 4 years and was initially planning to wait for the S10. But when the Note 9 announcement came with those massive specs I couldn't resist. Most of the extra features of the S10 don't really matter that much to me. The only real feature of the S10 I would prefer is Sammy's first 7nm processor. And I intend to keep my Note 9 for at least 3 years.
I have said this before but I find yearly incremental upgrades boring. What a massive and delightful experience exploring the Note 9 after the S5. And you know what? I look forward to being wowed again when upgrading my Note 9. Already, for e.g., there are rumours of 10/12 GB RAM for the S10 and there are 4 cameras for the newly announced A9 phones. So i really look forward to what is being offered in 3/4 years again.
Probably 12 plus GB RAM, 4 cameras at the back, a return to high MP resolution, a much improved Bixby, a lower than 7nm processor, 5G, further AI development etc. That's what keeps me motivated and interested and keeps me from upgrading regularly. When i upgrade my Note 9, I want to be just as I excited with all the new features and improved performance as I discovered when I upgraded from my S5.
You won't get that thrill upgrading every year.
If that helps anyone.