Earlier alts grew very well when bitcoin froze in place. And now they are just like bitcoin. Therefore, it is better to be in Bitcoin.
On a bull market mid/small alts will show better results in comparison to Bitcoin and top coins by market capitalization.
That is true but that happened during the bull market, now we are in a bear market and bitcoin is showing a better performance than altcoins in average, and this can be seen in the bitcoin dominance, during the bull market the bitcoin dominance was very low, this meant the performance of altcoins in average was better than bitcoin and now we are seeing the opposite, so if you want to be as safe as possible while still invested in this market then investing in bitcoin is by far the best choice.
But if your strategy requires to make the most money then you need to invest in altcoins as soon as an opportunity presents itself, you will be taking a huge risk taking into consideration the conditions of the market but if that is what your strategy tells you then you need to follow it.