DCA with USDT perpetual due to tax?

Hello,

I had the following thought the other day, but don't know if I'm missing something:

I built up my krpto positions in 2022 and 2023 and just hodled since then. On the one hand because of the favorable prices, on the other hand I really wanted to hold everything > 1 year to avoid paying taxes later (here in Germany I pay no tax from 1 year of holding, before that a variable tax rate, but in my case 45%). That's also the reason why I didn't think a monthly savings plan was such a good idea. However, I would still like to invest monthly, but as I personally assume that we will see new ATHs in the next 12 months, I have no desire to spot buy and pay 45% tax. So I came up with the following idea:

Why not just open a trade (USDT-PERPETUAL) every month with sum X with 1 leverage? You won't be liquidated at 0, but only a little just above it, you can leave the trade open forever and as far as I would only pay 25% tax (regardless of how long the trade is open).

What am I missing or can I play like this?