For me small or big investment will always mean money. It depends on what will be your investment, for short or long term and how you handle every problem that might occur. With $10 yeah its too small to start up but it will be the safest bet, but of course you know with that amount you didn't expect a high return. The least you can do now is to learn to play that amount in your hand and let it grow and then you can add some when things turn favorably.
If we're talking about gambling, starting small wouldn't only make sense but it's actually more logical than starting with a big amount. You don't want to have a big disappointment at the very beginning of it right? Takes away the fun off the bat
I think they are talking about investment on gambling sites, not to play gambling am I right? If yes then $10 is not worth to invest because it will give a very less returns. If we invest 1 BTC also our returns is just acceptable you will not satisfy with that returns. So according to me to make a good profit, we need big capital.