i don't really think using bitcoin as a retirement account is the best option because the future of bitcoin is not certain as nobody really the future. Predictions is possible but it is not 100%. It could be profitable at the longrun or not profitable at all. Well, everything has risk, you just have to gauge the risk very well before taking the decision.
You could argue the same about fiat money. Most people find their money has devalued over time and just look at pensions. Some people pay into them their whole life but when they get to retirement age they can't even afford to live on them because of inflation.
https://en.wikipedia.org/wiki/Pensions_crisis