Serious HODL question

Serious question about HODLing Bitcoin.

Our (spouse+me) current mortgage debt is $1.4M, at 2.6% interest rate – monthly mortgage payment is $6k. I expect to work for 10 more years, at the end of which the mortgage balance will be ~ $1M.

While we have retirement savings in 401k/IRA and in after-tax brokerage, I would prefer not using those funds for paying the mortgage.

Hence, I got into bitcoin. I have so far accumulated 2.65 bitcoins, which today is valued around $180k. If I HODL this stack for 10 more years, am I likely to have enough to pay my mortgage with it – I.e., about $1M.

I know that if I were to sell all my BTC at once, it will trigger a huge capital gains tax. Instead my plan would be HODL for 10 more years, and if the value of BTC reaches $1M or roughly the same as mortgage balance, then start DCA selling the BTC each month to pay the mortgage? Say, sell $9k per month of BTC, set aside enough to pay taxes, pay the remainder towards the mortgage for 15 more years.

Am I on the right track here? Or is BTC so volatile that a regular DCA selling strategy not likely to work out? In which case, should I just sell my BTC in a year or so and move the funds over to something less volatile like SPY?