It's not exactly a wealth tax, but it's also hard to consider a capital gains tax because you can't deduct losses. Treating other investment products this way would probably have horrific results, because it heavily disincentivizes taking on any risk.
If, on the other hand, you put down your money in bitcoin or at the online blackjack tables then you're gambling, not investing. Win or lose, your gamble creates zero domestic growth. Why should any government incentivize that?
Well maybe they shouldn't, but it's shitty to apply this kind of policy retroactively. (I don't know when they actually announced the fact that you can't deduct losses.)
"Generally, the Finnish legal system does not permit ex post facto laws"
> In civil matters, such as taxation, ex post facto laws may be made in some circumstances.
Instead, investing in stocks and cryptocurrencies benefit the economy in very similar ways. In both cases, companies hold on to these assets, and can sell them to raise money for doing projects, buying companies, hiring employees, etc.
But government's probably shouldn't be incentivizing or de-incentivizing any investing. Saving money is sometimes the best thing to do with it.