Unfortunately this year is bull season, so it's not really a good time to buy Bitcoin, instead it's time to sell.
You can buy Bitcoin in the next year, it's bear season.
If you not believing in 4 years cycle pattern, I don't think there's a best way to buy Bitcoin at the bottom and sell Bitcoin at the top because in trading, you're predicting the price in short term, not long term.
If you can buy low, sell high, you will get profit and it's good, not bad.
In a bull market, chances for buying low and selling high are a lot, but I understand your post about risk of failing to time the market. It's true, but if you don't target too high exit price, you will have good chance enough to take profit.
Generally, DCA is a good strategy and it's more helpful for long term investors who are less affected by short term price changes, in either bull or bear market. DCA strategy can help long term investors to average their entry price, and it gets benefit from long term bullish trend of Bitcoin.
https://charts.bitbo.io/yearly-candles/