the simplest and easiest way to invest I can think is buying or earning bitcoin in the low price, and hold it for a long time. no doubt, many people make profit by doing this. but I myself invest my bitcoin into a business. I sell things and get profit. it is another way of investment, but not bad.
Yes that is the simplest way of investing in bitcoin but the thing is that we can't buy bitcoins at a very low price today as the price keeps on increasing. Maybe better to focus more on some other ways where you can good profit like trading. While you have funds for holding, still you need to allocate some of it for trading.
The best investment strategy is to put money into bitcoin, investing in bitcoin is realy profitable if you work smart, first you buy bitcoin than you take some of it and use it in trading on short term bitcoin and you save some, and then use the profit to buy more bitcoin and keep repeating the same until you become rich.
That's right, if you are that risk taker you will invest almost half portion of your total assets in bitcoin. But of course there are smart people who had invested almost everything with bitcoin and now they are earning the profits and trust that they gave to bitcoin. By simply just holding it for a long time and sell it after wards made them rich.