Ask HN: $500k cash – what to do with it?

I'm 30, married and planning to start a family next year. I want to work hard now in exchange for better financial stability later. However, I rather spend my time on learning how to use money to make money, than taking on a job. Although if I have to, I can make a decent salary. I have ~$300k in mortgage, no other debt, monthly expense is ~$5000 (includes mortgage, tax, utilities, food, entertainment, etc). Assume I am the sole bread winner. No other assets. Able and willing to take a reasonable amount of risk. Parents can take care of themselves financially, only dependent is spouse and future kids. Thanks!