Investing in bear market is good but could also expose someone to using up their back up funds or emergency funds. It is good to go a little further on bear market but it is not advisable to go extreme during the Bear market in order not to see off your bitcoin due to emergency situation. Get very used to not investing beyond your discretionary income no matter the market behaviour. Bear market will always come any other time. So ensure you don't sell off soon because of Bear market.
I am a little confused about what you mean by "acting extreme when the market is sluggish", if the funds used are prepared for long-term investment or in other words the funds are cold money, isn't that a reasonable action?
A sluggish market is a good moment to accumulate assets, investors who have prepared everything will take advantage of this moment to buy Bitcoin at a low price.
Investors who invest in the long term will not be affected by the decreasing prices, they will hold their assets until they see the expected returns again. If possible, they will actually buy as much Bitcoin as possible in preparation for reaching ATH.