Do I still owe taxes if I “lose” my Bitcoin?

If I moved Bitcoin or some other crypto currency from a centralized KYC exchange to a cold storage wallet and the tax man comes knocking at my door in a few years, can I just say that I lost my Bitcoin in a boating accident? Can they tax you for something you no longer have?

Btw to my irs agent, this is for educational purposes only so please don’t send the black helicopters to my house. Thanks