I understand the lure of the tax deductions and even possible employer matching within retirement plans such as 401k.. even though your retirement plans are likely different from the ones available in the USA and surely not everyone has access to various retirement investment funds.
I am thinking that I would have had been distracted if I was still contributing into my 401k from 2014 and thereafter, which I was not, and so bitcoin became a substitute for my 401k contributions that no longer were available to me at that time.
There can be employer matching up to 5% or something like that, and depending on income there can be tax benefits (deferral) up to $23,500 per year, which surely can be tempting to get the tax deferral up to the limit, even though it may well be better to invest into bitcoin rather than receiving the tax deferral benefit.
Here, there are 2 reasons: income tax and savings tax. Income tax means you save 37 or 49.5% tax on the money you put in the pension fund, but your pension will be taxed when you receive it (at a slightly lower rate by then). Savings tax is currently 2.12% per year on all your investments (like Bitcoin).
That's 2.12% on the total value, not on the return. Next year, they want to raise it to 2.8%. Yep, we have a very greedy government. Anything in your pension fund is exempted from this tax.