Personal conviction can not stop one from panicking or making irrational decision especially when it comes to Bitcoin investment, imagine after investing when the price is so down and then later surge to a high price and again, all of a sudden the price decline or dip below the point you started investing, you don't need anyone to advise you at this point because their advise won't change what you are thinking at that moment even though you have a conviction and understanding of what Bitcoin is.
Maybe you have a different understanding about what personal conviction and understanding of the market/Bitcoin really is. Because for me, when someone has a good understanding of the market and then have a personal conviction, first of all, the person would understand that they should only invest with what they can afford to lose, secondly, short term fluctuations are basically nothing new as far as Bitcoin is concerned, and thirdly, no matter how much the price declines, it’ll still most likely surge again and always establish new ATH, even if it might take time for it to do so.
These knowledge and understanding of the market helps you know what to expect, and so when they eventually happen, you’re not surprised because you already expected it, so there’s no room for making irrational assumptions and decisions anymore. Besides you’ll know already that these fluctuations and volatilities are only temporary, and since you already have that personal conviction, you’ll already have a long term commitment and plan, so your mindset is on the long term and not what happens in the short term.