Those who are still holding Bitcoin in large quantities in their portfolio are really trying. As the market is falling we should endeavor to get altcoins which has strong management team and unique liquidity to scale through when the market recovers. This is the best time to keep buying as the . market goes down, not just a single project but different one.
I know it's always better if we can diversify our portfolio as much as we can, but selling bitcoin just to enter in a more risky investment which is investing in altcoins, i think that won't work for me. I have been struggling in the past just to own bitcoin and now that i have it already, i won't never sell it at a very low price. I think i will have more chances to buy altcoins when the market will fall even more, so i think i will only wait for that time.
The main concern also here is that the OP is quite new to this market.
So right now, would be hard for him to spot valuable alt projects because it would take time and experience before you spot one.
The better thing to do right now, is observe the market, and do your study with these popular alts, assess their potential in the market.
Hold to your btc for the moment. And once you are quite confident with yourself, and learn more about the value of investing alts, then, you can slowly diversify your portfolio.
Better stick to alts that have tangible use case or application rather than new alts that are still promising to deliver their goals.