Yeah, that's right, but not all of them will take the advice of only investing in Bitcoin. Some will still end up putting their money into some altcoins, and it's after they have been disappointed and their money has been lost that they will begin to feel regretful.
Bitcoin is the ultimate of cryptocurrency and that is why you will see that those investors who invested in altcoins due to greed because they want to get rich quick, after they have been disappointed and regret their actions, will come back to invest in bitcoin because they have realized their mistake and want to make things right.
Bitcoin investment needs patience, and it is worth waiting a very long time for it to mature to that target that we want, and this can be achieved by regular DCA weekly or monthly because it a a real life investment. This is why it is better to start investing now than think of other altcoins because they can never be like bitcoin.