Bitcoin is not a get rich quick scheme but has been the only crypto asset to work well as a long term store of value for several years now. Other alt-coins may have greater price increases in the near future but they're all less mature and it is basically a gamble at this point.
If you want to risk the less possible downside on your capital, you may want to chose the more mature asset that is bitcoin.
Having said this, it is important to note the upside potential of bictoin is still enormous as it is still only a niche asset that can grow several orders of magnitude.