selling to buy back cheaper is a dumb idea, and it is contrary to what any newbie should be doing. We should tell them that is dumb.
Selling lower than you bought is a dumb idea, so we should tell them that is dumb.
Failing/refusing to continue to buy at a reasonable rate is a dumb idea, so we should tell them that is dumb.
It is good that you are saying this, even if it sounds like a bitter truth, and most newbies must have fallen victim to this in a bid to think that they are being smart.
Rushing to sell below the price at which one bought his Bitcoin is dumb. Even from basic economics, when the selling price is less than the cost price, it is only foolish to sell at that price except you are dealing with a perishable asset that can't stay after a certain time. Is Bitcoin in that category? For Bitcoin, even letting it stay is the best way to remain in profit, which makes it dumb to think of selling too suddenly.
As opposed to selling when the price is below what you have initially bought bitcoin, it should be counted as an opportunity of adding more bitcoin and buying at a cheaper rate. Patience and discipline are what will help one make the best decision when the thought of making a dumb decision comes in.
Even if you're in profit i.e the price off bitcoin is higher than your entry point, you shouldn't think of selling until you have over accumulated more than enough Bitcoin in your possession. Any investor in his accumulation journey shouldn't sell buy only to keep on accumulating without relenting. This is why DCA method is very convenient because it gives you the opportunity to continue buying weekly or monthly regularly irrespective of the price of bitcoin.
A new investor should focus more on increasing his bitcoin portfolio overtime because if future bitcoin price will go beyond our imagination. If you are still in your accumulation journey and you sell very little because you are in profit, you might not be able to resist the temptation before you know it, you are becoming a trader instead of a long-term investor.
Any investor that sells too soon will regret his actions in future because you will be left with very little bitcoin. This is why your main aim is be a long-term holder who is only accumulating bitcoin, and also looking for other means to improve his income in order for him to be able to invest aggressively when the time comes.