I just saw this thread and I know you must be smiling now if you bought the dips in December 2018. Almost everywhere is green, at least better than December 2018. Investing in good crypto coins is very profitable, just hold and don't sell when the price is lower.
Investing in Bitcoin is always profitable if you are ready to wait for years. It will grow, but not very soon. Buying BTC for 8K (+/-) now, you do not waste your money. I guess Litecoin and Ethereum are also good investments now.
Although I tend to agree with you, there is no such thing as a safe bet. Something else could be around the corner and beat Bitcoin. It is not impossible even though I don't think it is likely.