The amount we invest depends on how much of our discretional and disposable income we have after taken care of our personal needs and a provisional emergency funds, yeah you right about saying that those who have lesser risk tolerance level we tend to invest more than those that have higher risk tolerance level which differs individually even in terms of our income flows and expenses so any one can only invest the amount that suits him or her in terms of income flow, psychology, risk tolerance level and investment goals and objectives.
It doesn’t really matter how much we start with and all that matters is to invest in bitcoin and gradually we can build our portfolio and accumulate more bitcoin regardless of one’s risk tolerance level. When investing you should try not cross your limits and only invest what you can at a time.
So if you really want to be comfortable then just set it for investment without having to think again to be used as trading especially if we don't understand the trading scheme because in the end it can be like gambling where you only guess according to your instincts.
I wouldn’t advise a person who lacks understanding of trading to think of channeling their investment funds into trading because of the risk involved, trading has higher percentage of risk than Investing and holding and also trading carries more work load than investing because there are lots of things to be learned and understood before one starts trading and even after having the required knowledge the risk is only reduced and still not equal to or less than that of investing. Trading requires practice to perfect to some extent and to achieve this takes lots of time and effort and at the end success is not still not guaranteed. This is why beginners are advised to accumulate bitcoin to hold instead of trading.