Tldr: we are at the point where it likely is worth it to diversify.

In the traditional stock market one can very easily reduce risk, and make slow and steady gains by diversifying your portfolio. This is how index funds operate. You get a bit of everything, and will perform at the same level as the market does. 

In crypto it is a bit different, due to bitcoin having a huge portion of the market cap - currently around 60%. The 2nd largest crypto being etherium with only 12%. This basically means that bitcoin has the largest influence on the crypto market cap. When bitcoin falls, the market goes with it, because people sell btc for FIAT.

If you held just bitcoin until now, you had most of the market covered so to speak. And to top it off in the past 3 years bitcoin has performed twice as well as the market average. So historically speaking, it was not worth it to have a diverse crypto portfolio. Sure, if you picked the perfect alt coins you would have made more money. But at that point it's basically down to being either a lot smarter or a lot luckier than the average investor - it's possible, but highly unlikely.

So if until now it has not been worth it to diversify, why should you start now? With the confidence in crypto increasing - proven by the fact that big firms are buying in - we will get to a point where a dip in bitcoin will not have a negative effect on other coins, but rather a positive one. Let me explain: if the confidence and crypto as a whole gets big enough, people will not sell bitcoin for FIAT but trade it for another coin. We can already see this happening with ETH losing dapps to competitors like ADA. Ergo the market cap of all coins together will not fall, only the dominance of bitcoin.

What does this mean? It means that if you agree with my train if thought, being well diversified in the crypto market will actually start reducing the risk level of your investment! On further detail as to how to diversify within crypto keep an eye on my blog.