The only altcoin that do not have the chances of loosing value are mostly some of the top altcoins we already have in the market. Anything more than those, get to be under probability while investing, that doesn't keep the investor at peace because he never knows if the altcoin could worth more while holding or reduce to a point where even recovering back the invested amount is impossible. Bitcoin offers this comfort, no matter the price reduction, there will definitely be a good bull run and profits is made.
As you have said, there may be some good altcoins, but as for me, I don't believe in them. I have seen different altcoins that have made a good name for themselves as coins worth investing in because of their years spent in the crypto industry. But where are they today? They became 'lie coins.' So, as for me, I don't really believe in all these altcoins, and I will never advise anyone to invest in any type of altcoin. I feel they are all heading in the same direction; it's just a matter of time before they start messing up.
From my observation, some people who invest in these altcoins are usually those who are eager to make it quickly in the crypto industry, not realizing that they are putting themselves at high risk. As for me, it is better to take less risk and expect gradual profit from Bitcoin. I know that if I hold it for a long period of time, it will eventually bring me more profit.