The data supports that on average, they do worse, but I don’t think average is a good metric (and why I won’t belabor this with any supporting data). Much like the affluent usually live longer, poor market timing likely has a high correlation with low education, low fortitude, and low wealth.
I have no data that support this hypothesis but I can state anecdotally and based on my 20 years of experience, it is those with the least to lose and the least investment experience that are the most likely to lock in losses when they should instead stay the course - and they are also less likely to see a market sell off as a “sale” or otherwise good time to buy.
Edit: I will also add that some of them are also the least likely to accept advice when it conflicts with their world view. I’ve had otherwise conservative clients profess religious like belief that the admin has a master plan for the stock market. They have no idea what that plan is and cannot articulate it in any way, but I can recall four in the past few weeks that I advised to get more conservative before this mess and they did not listen because of their faith.