Buying bitcoin for me is not a one time thing where I dump a lot of money in at a certain price and that would be it. Instead buying bitcoin is a constant operation whenever I get some extra cash that I dump and I have been doing it ever since price was about $400 back in 2014 and continued falling down to $150 and I kept at it until $60k and will continue dumping fiat until bitcoin is $10 million.
Of course I don't only buy bitcoin, I earn it and sometimes it is profit from trading shitcoins. So it is hard for me to come up with an average.