In my opinion, you should use $ 7000 to invest in Bitcoin. I think Bitcoin price can increase to $ 5,000 in near future. So we will make a profit from buying Bitcoin.
Bitcoin is the first thing to kept if you are willing to take your journey in a much longer time frame, as most believe that this coin can increase larger than we expected after some years, and aside from bitcoin you can choose around the top 20 alts around you can split little by little or select 2 or 3 more coins which you think that have a good potentials after some years, buying and holding till you achieved decent profits.