it is a good decision that you are planning to sell altcoins and buy bitcoins. However, altcoins are risky, so don't be too greedy, if you are too greedy and try to make more profit, you can face huge losses. Because I don't see good long-term prospects in altcoins, but bitcoin has good long-term prospects. You have invested all your money in altcoins, while other people invest 80-90% of their money in bitcoin. However, I will say again don't be too greedy, because if the price of altcoins drops, it is not easy to recover.
Now no one can predict what the price of bitcoin will be in 2029, but you can expect to make a lot of profit.
That is actually an insanely good plan. Alts will go up a lot, and if he could do trailing stop loss, that means he could start selling when it starts going down, sure he will make a small loss, but more like 5-10% at most, that way he can get out when it starts to crash, put it all on bitcoin at the bottom, and make a ton of money on the next bull run. Many people will end up hating that, but it is going to be great for the long term and shouldn't really bother us too much.
We should be able to actually get great returns if we did this and should be making some real money. If we do this then we are going to get a great price for getting back in as well. So, it is not really complicated situation and could be very well for us.