In my opinion, the cryptocurrency market is still very young and the first competitor to Bitcoin is Ethereum. Perhaps in the near future the situation may change dramatically, because compared to Bitcoin, Ethereum has a much faster transaction speed and the transaction cost has decreased again. Of course, scalability is still the main problem on the path to mass use, as well as before attracting large sums of money from a large business. But I hope that the team will do everything to solve this problem.
No, because Ethereum was made too centralized, reflected by the fact that they can undo blockchain transactions on a whim, which permanently damaged its reputation. Oh and infinite supply...
Centralization is the biggest weakness of many altcoins, but not the only one. I don't even know of any altcoin deserves the term "competitor" at this point, as they all combined keep moving less than Bitcoin alone.
Bitcoin isn't perfect but so far the alternatives have been far from being better. This is bad for everyone, of course. Perhaps another one will come made by (yet another) anonymous developer who will disappear permanently following Satoshi's footsteps. That would be the first step in dismantling any scam or profit scheme accusation (ie. Litecoin guy selling his Litecoins). Having its own blockchain (and not piggybacking on anyone else's as "token") probably helps. Then being centralized, ie. unstoppable. A well made code that will keep the coin design following its route whenever that may be. No identifiable individual or company you could destroy to destroy the coin, basically the opposite of many altcoins.
And even after all that, it takes something especial to be recognized by the community. Faster transactions? Bigger anonymization? How about security and redundancy, ease of use, etc.
If Satoshi were to make Bitcoin today, what would he/she/they made different after magically having earned these 10 years of past experience? THEN we MIGHT see something remotely resembling competition. Most of what we have now is useless and or not trusted, and there is the addition that there is simply too many, among all that garbage may a gem remain hidden, but most people can't spot it yet.