I think that buying and holding Bitcoins would be your best Option if you want to earn good amounts of profits as Bitcoin, without any doubt if the most popular crypto available in the market. It has alot of potential to grow and you can easily expect it's price to be above 10,000$ by end of this year or so.
You can also buy and hold some progressive altcoin like ethereum if you are looking for short term investments but i would only recommend Bitcoin in the long run.