How do we determine if a coin or token is suitable for investment? For example, trading volume, total supply, number of holders, etc.
All these as you have mentioned were part of the measures taken to make an investment in any coin, the more the research you do and how convinced you are about that particular project depends on whether you will opt in for it or not, some will say that they are liable for taking risk on any coin they are investing, while some would have been well convinced about a certain coin from the research made before they chose such for an investment, so everyone has his own measures taken into consideration differently.