We can't say instant. How much returns you are going to earn depends upon how much you invested. Someone earning huge returns would already be rich. But people who are not rich might be investing less and hence they can't get rich instantly. But yeah if you invest for 5-6 years today. Returns would be huge and can make anybody rich.
Yes you are right a long term investment in bitcoin returns a huge profit and it depends on the amount of investment and strategy. Many people who I know have earned more profit from bitcoin than their imagination. But one thing everyone must remember that success does not come overnight it requires hard work, dedication and patients that leads to success.