In fact, I have started buying 3 days ago... small amounts monthly. All my BTC before were earned, but want to get more as I realized its potential to go up.
Well, if you have a lot of money I suggest to buy more bitcoin because having a lot of bitcoin can help you to become millionaire. In addition to that, if you can't afford to buy bitcoin there are some way to earn bitcoin. You can gain bitcoin in faucet but it takes time to wait.
Why only buy Bitcoin helps me become to millionaire? You need have to remember the current price of Bitcoin very high, not cheap like past price. Therefore, if you use that amount Bitcoin for trading or investment, I think you will have opportunity get rich, only holding Bitcoin at now cannot do that, you need wait long time, maybe 5-10 years is possible.