I would say it’s a wrong reasoning. If you want to account for taxes paid at the exit, you should also consider taxes saved in the first place. As we know, contributing to the 2nd pillar, saving on taxes and withdrawing after 1 year the same amount can easily result in 30+% of return due to different tax rates saved and paid. That’s why it is de facto forbidden.
I didn’t want to mess with these tax rates also because it is a general feature of pension schemes 2 and 3, not related to what kind of assets you have there.
In fact there is another very distantly possible issue discussed: that with 3a you pay taxes on the whole amount withdrawn, i.e. it becomes a capital gains tax. We tried to do some estimations, looks like that for 40+ years the 3a with 100% stocks can grow so much that due to the exit tax you better invest in a taxable account.