1. As long as it can't get back to you, you're good. But if there is a small chance, keep a log of how much you bought for how much so you can prove it was a loss and not a 100% gain.

Also keep in mind:

If you buy 1BTC for $100 and gamble it and lose it all when the price of 1 BTC = $1,000, this is not a loss of 1 BTC, it was a gain of $900. 💩

The government sees in dollars, so to them you: sold 1 BTC for $1,000 making a profit of $900, and THEN gambled away $1,000.

2. When the taxman sees you living it up, they'll wonder where the money came from. If it isn't obvious to them, they'll suspect that you're tax evading. Don't need KYC to report you for you to get caught. KYC would confirm their suspicions though.