Procrastination which is said to be the act of delaying something important despite knowing the consequences of doing so, is one of the reasons why many people miss out on big opportunities.
I don't think it is the procrastination that's playing the huge role as to why some investors did not but bitcoin earlier. I think it's more of a doubt a fear of bitcoin's high volatility. Procrastination is different that fear and doubt actually.
Also, some people might have missed buying while the price are still low because they are looking for the bottom. We all know finding the bottom will never going to be easy, because you will either hit it or miss it. DCA method has always been a good strategy to accumulate bitcoins during the bearish trend.
There are still a lot of reasons why some people have doubt bitcoin despite of the fact how far bitcoin have gone since 13+ years ago, but then again I don't it is procrastination.