I think the biggest feeling of regret is the FOMO for having delivery right after a price drop/new feature change/option/battery is announced. When I got my 2018 Mid Range Model 3 in Feb 2019, nearly 2 weeks later a large price drop was announced as well as discontinuation of the Mid-Range with white exterior being the default option(where as it used to be a $2000 upgrade). Same sentiments were thrown around come time of heat pump being announced, new interior door trim, power trunk(for M3), heated steering wheel, trim refresh, and so on. It is a really shitty feeling to know your car just got dated and isn't the newest version, and although that comes with any other car brand, you usually would get a discount or the newer version is more expensive