In short - no, they shouldn't be kicking themselves.
I'm not sure exactly what this post is intended to accomplish other than trying to make people feel bad. When I upgrade systems I typically upgrade the motherboard, CPU and RAM together because of how much time has elapsed between builds. I was dead set on a 3700x until I considered the only time I stress my PC is while gaming, so that made the 9700kf the ideal choice for me when I bought it about a month ago. I would buy it again today because anything new to the market in the past month is still in the early adopter phase and doesn't have a proven track record yet. I don't have any regrets. There is always going to be a next best thing coming along. You can always wait to upgrade if your system is functional. The system I upgraded from was server hardware from 2012. I waited a very long time to upgrade, which is the thing to do from a value perspective.
I can't speak for the community, but my build from planning to test bench was about 2 months in the making, and at this point I'm still waiting for the GPU water block to arrive and the case to go on sale. I wouldn't say there is any lesson in patience here with the normal progression of how quickly new technology is developed and brought to market. Most people with experience building PCs (and I would venture to guess a lot of those who don't have any experience) know that something better will be coming out probably sooner than later. Don't feel bad.
Which Intel CPU did you buy?
0Zx