Sounds like a solid philosophy, and you're definitely right... don't bet more than you can afford to lose comfortably.
This is super common advice, I don't mean to pick on you at all.
I think it's terrible. What's wrong with taking chances, risking pain? Does this advice mean that you shouldn't hike in the wilderness or ever ride in a car? You could lose your whole life.
Besides that, whatever you do has some total risk. Leaving your wealth in the generally accepted forms just means that if you get wiped out so will everyone who might be able to help you.
Be bold, temper it with a little thought. No matter what you do you could lose everything.
"Do not invest more than you can afford to lose comfortably." This common advice is really good advice. There is a multitude of reasons for that.
Admittedly, it is not the most enlightened of phrases; actually it is meaningless to an expert at statistics. Such a person will try to find an exact solution for his personal risk strategy. But as a simple phrase, spread as a meme to help people, "do not invest more than you can afford to lose comfortably" is a good choice.
There are important things people who do not heed this advice should know at the very least, but often don't.
- The Kelly Criterion helps to determine the height of wagers in probabilistic bets. An important property: betting a little less than the optimum doesn't hurt much. Betting above the optimum does.
- To even be able to use Kelly -- and for any kind of speculation in general -- it is useful to do a self-benchmark. Know your own precision and also limits on how well you know it. Overestimating oneself is one of the biggest flaws of humans, so be careful and rigorous on your self-assessment.
- Similarly, do not forget about any additional uncertainties from the surroundings. Expect the unexpected, not just on one market, but in personal life and everywhere else too. When going in deep, hidden risks that are normally acceptable suddenly become very relevant.
- The personal value of wealth to any human diminishes with wealth and grows with poverty! Your last bit of money in times of need becomes more valuable than whatever was spent before.
Of course there are risks everywhere. Speculating with a notable portion of one's savings can be a good idea. But why push a lot into a single thing when a diverse strategy has much less risk?
"Don't put all eggs in one basket" is a similar wisdom. Sure, it's not universal. Some people can prove their one basket secure. But then, better be sure to never ever make a mistake.