experts predicted with Bitcoin expected to reach 1 million by 2020.
Not experts, AFAIK it's only one single guy that predicted bitcoin will reach $1,000,000 three years from now.
But after that it has been a blood bath. There have been many factors contributing to it like security flaws in exchanges, sanctions by governments, huge sell off by holders and many others. The Crash has been very bad and it has affected the confidence of investors interested in buying currencies or investing in the projects implementing blockchain.
Right, these incidents gave a huge to the price of bitcoin which made many new investors to doubt it.
Now that there are many altcoins in the market and are at a very low price, is it safe to start investing again? Or will it slide further down the rabbit hole?
Investing during the bear market is always the best time to do so.
Don't wait for it to rise again before investing, when bitcoin shows some increasing attitude/chart, alts will come after it.