Is it really a big mistake to sell portion of your bitcoin and then rebuy back when the price has dip?
In my opinion, it is not a big mistake because, of course, selling part BTC and then buying it back when the price drops is possible, but we can only do that if we can accurately predict where the price will go. However, if we can accurately predict the price of BTC by doing that, then we will definitely increase our BTC holdings.However, for those who are less skilled at predicting, it will certainly make us regret selling BTC. For example, if we sell BTC and the price then rises sharply, we will definitely suffer a loss. The point is that if BTC has been sold, then when it is bought back, it will certainly result in fewer BTC being purchased. So, it depends on whether we can predict well or not.
However, in this case, the decision lies with the BTC owner, as selling part of the BTC is acceptable as long as a profit has been made.
Your re beginning to sound more like a trader than an investor to me because a true investor in Bitcoin wouldn't be timing the market to Buy Bitcoin and later sells it for cheaper gains. I believe this is a common strategy by traders. By trying to predict the market accurately, only buys when it's Dip and sells it later it starts appreciating in value prove you're simply a trader in disguise.
However I don't agree with this your strategy of accumulating bitcoin for the short term because it's risky and unprofitable. If you're not investing in Bitcoin for the long term,then you're simply gambling with your funds.