You have to decide NOW how many bitcoins will make you rich in the future because it's getting to the point where an upper middle class American or European can no longer buy a full bitcoin.
Anyone have any ideas how many you'll need to be rich in 2020 and 2025?
There is no require or fixed amount of bitcoin that you needed in order to be rich in 2020 or 2025 because it doesn't matter if you only got 1 bitcoin, the only matters is how can you grow that bitcoin and also save some bitcoin for long term because if you do that two things then it will be easier for you to be rich in 2020 or even earlier.