uhmm,its a part of their plans they will tell other peoples that "Bitcoin is dead" so other bitcoin user will panic selling their bitcoin then some peoples buying bitcoin because it will get low value then they will get so much bitcoin then they just need to wait to bitcoin rise up again then sell they bitcoin in higher value 
they will gain much profit by doing this 
You are also right but there are some developers who have their own currency and they are thinking that they are able to replace their currency with bitcoin but they are at wrong because if bitcoin will survive then people will also believe on other currencies and if bitcoin is harmed then no one will believe on any crypto currency forever. they will gain much profit by doing this