A bear market is a great time for accumulation, especially if you believe that the fundamentals are strong, and you can afford to hold for the long term. You can take chance and speculate by shorting the price , but you need to understand price movements to do this. The other alternative is a variation on price averaging. The price never goes straight down, but the drop includes periods of sideways movement, and price corrections when the price goes up. If you buy when you think the correction is near the bottom, and sell when you think it has gone up enough, then you can increase the quantity of Bitcoin that you buy. If you never take a loss, but move the coins that you can never sell for a profit into a HODL wallet, then you are just boosting the number of coins that you would have purchased as part of your averaging.
Note that this is an ultra safe approach, and is based on the opinion of someone who is not a professional adviser, and who isn't too good at chart analysis. With this approach, you shouldn't use money that you can't afford to lose, and you are prepared to tie up for a couple of years or more. Also you need to be convinced that the long term trend for Bitcoin is bullish.
Like you said, price averaging is only good for long term portfolio building, but for short and mid term investors, even with strong fundamentals the temptation to build one's portfolio in a bear market isn't as strong as the will not to lose money. IMO tho, for short and mid term investors or traders, profit is key to sustenance, so I recommend the fluid approach. Dance with the market. Buy and sell even at the bottoms, and track profits - it's called being penny wise. But it takes gut and a level of risk awareness to be efficiently fluid with the market, hence, investors should groom themselves with every technique available to asset management.