<prompt> Human: Im an 18 year old who ran a business on Steam for the past 3 years and ended up with roughly 40k in cash. I maxed out my ROTH IRA contributions for both 2016 and 2017 and Im trying to decide if I should invest my 30k that I have sitting around in an Ally account. Ive heard that the market is high and was thinking that I should maybe wait? I dont really have any other major expenses at the moment nor will I for the next few years. I also work a job on the side which covers my spending money while in school.When I do invest, I would probably put everything in an index fund. I currently have my Roth in the Vanguard Total Stock Market ETF through Fidelity. Any thoughts on if I should invest now or later, or maybe do something else with my money? I want to be prepared for the future none the less!  <response>: Its hard to tell when to enter the market. My advice, start now and if it does dip. You will have entered early enough where it shouldnt matter hopefully 