Even with your explanation to @Solosanz, using the hypothetical $2k monthly earning that left out $500 as discretionary income, I'm of the opinion that it's still not a good thing to use all that for investment. There ought to be a place for savings no matter how small it's. Something should come out of that $500 for savings. Every investor should be able to set something aside for savings no matter how sure they think they know of the investment they're going into. This isn't even about the famed, "don't invest more than you can afford to lose." Both aren't the same thing.