Add me to those that would like to hear more about your future plans. Right now, you are making money, but education (college, a trade / apprenticeship) is going to be critical to get you to a place where you can stand on your own two feet.
At 18, I left for college with all of my odd job / babysitting money invested in the market, and it was a $30k slug by the time I got serious about early retirement in my late 20s. So, I understand wanting to get your money in the market to work for you.
However, I disagree with others that you should be hiding cash around the house. As long as your parents cannot access the money without your permission, you should be okay. If they can, consider putting it in a 1-year CD, sometimes those are more difficult to get out of (account co-owners may need to be involved.) Another alternative would be opening a small safety deposit box and putting the cash in there. However, you have to acknowledge that you are then getting negative returns on the money, not great.
Importantly, you have a great attitude, and I agree with others that you should avoid being preachy. Keep your head down, nose clean, and plan for your future. Your future may incude having to support your parents, so I recommend (say, in 5 years) having a come to jesus discussion with them. Suze Orman actually has some decent scripting on this. You want to emphasize that you love them, but they need to ensure they are able to support themselves in old age, and that you are willing to do what you can (non-financially) to help them, etc. i think that is going to be your big challenge as a kid of 40 year olds with $10k in their 401k. I had more than that at 18. :(