The price of Monero rose more than 120% in the last few days. It is a good coin with anonymity, It might replace bitcoin.
I highly doubt that. We see huge spikes and falls on daily basis on many alt coins, and this 120% rise in price would probably be another pump and dump attempt.
Yeah a lot of people just take advantage of altcoins because the price is so volatile, it can be easy to manipulate and make a profit if you know what youre doing. other than these, I do not find any advantage of altcoins. So, they are never a threat to bitcoin. Bitcoin will never be replaced by any altcoins.