Yes, its a taxable event. The ideal holding period is 10 + years, or decades. However, at some point one must take profits, if the intent is to retire or use the gains. All I am saying is that for those who plan to take profits next year, have a plan and dont make any emotional moves. This thinking is based on the current 4 year cycles where BTC peaks and then goes into a bear market, followed by 3 up years (and we are coming to the 3rd up year in 2025). The 4 year model of supply shock is expected to break down, since it was based on a shrinking of the mining reward every 4 years, the current mining reward is only 450 BTC/day, a small amount, so its effect will be negligible going forward and from the next cycle (2028), when it shrinks to 225/day. The ETF's on somedays are buying 5000 BTC/day, so I think the reward no longer plays a big role.
All of this could change, if Trump establishes the Strategic BTC Reserve (SBR) which he has promised and his Treasury secretary supports. Several states such as TX, PA have their own bills cooking to establish the strategic reserve. If the SBR is established, then the above 4 yr cycle will not hold, and
BTC goes on a pathway to a Million over the next couple of years or less. Which is why I also said, dont sell everything.
P.S. The above is my current thinking, but I do not have a crystal ball, so please do your own research