I have being giving this question a thought for days now, if other altcoins can be a threat to bitcoin especially ethereum which some folks are saying is a threat to bitcoin, and I came to understand that, the reason why other altcoins can never be a threat to bitcoin is that, bitcoin being the first and largest cryptocurrency has survived external attacks and attempted ban from government, which no altcoin has face such attack, because bitcoin has already paved way for them.
bitcoin has also overcome many social and political trials, which those trials almost led to the shut down of bitcoin, yet bitcoin gain more attention and adoption, which no altcoin has gained such attention and adoption, not even ethereum which some folks out there are saying is a threat to bitcoin.
Bitcoin has already dominated the crypto space, because it has always remained active and accessible without interruption, and to my own best of knowledge I don't think if companies like Facebook, Microsoft and Google have achieved this level of reliability which bitcoin has achieved so far, talk more of altcoins.
And I we also like to see more contributions from members of this forum, let prove to some folks out there that altcoins can never be a threat to bitcoin, because alot of folks out there are saying that ethereum will be the end and the down fall of bitcoin, which I doubt.
Being a threat to Bitcoin does not mean they'll take the global space of Bitcoin. Bitcoin is so big right now and it has the largest market share, Bitcoin is decentralized but of course there's room for competition.