Why shouldn't I invest 100k into BTC?

I will receive an inheritance of €100,000 and I am considering buying BTC with it and let it sit for a few years.

It's extra cash that I didn't expect and that I don't particularly need at the moment. I am in my thirties, good job with a nice enough salary, I have six months emergency savings (probably more than I even need considering EU safety nets). I invest €1,000 each month into SP500 etf.

I never look at my portfolio except when I buy and I'd treat my btc wallet the same. Not planning on buying property as renting is cheaper in my city due to the insane loan interest rates.

Why shouldn't I dump it all in BTC? Explain why I am an idiot.