I want advice from all veterans here as what best strategy can be for BTC selling. I want to sell at every pump and buy on every dump. How can one make sure he does not lose it.
It's possible to do this, but it requires patience. If you can be patient enough to hold after buying for a long period until a new ATH is achieved, you can sell and wait for a long period again until a price correction occurs or a heavy crash or slash down in price occurs before you enter back into the market.
It's possible, but you can't always be perfect; in some cases, you might sell a bit too early or late, where the price will go up again, or buy too early and the price drops down more, but as long as you buy below what it sold earlier and sell above your purchasing price, then you are making a profit, and that's all that should matter.
Not just patience is required here. He needs to have a steady income flow so that he will continue buying Bitcoin until a new ATH is achieved. For cases where he might see a dip that is comfortable for him, he needs to use some reserved money to buy aggressively. This will be much better rather than waiting for a time to buy, as there is no perfect time to enter the market. There is a saying that preparation meets opportunity. He has to be prepared, because anytime might be a good time for him to start buying.