I have often wondered if the cronies of Aldor, his younger brother, got Baldor in his cups and then by insinuating that it would be cowardly not to tread the 'Paths'. This would have been to get the throne for Aldor when Brego finally died, which he did a year later, of a broken heart over the loss of Baldor. This conspiracy theory is probably hogwash, and the truth is probably more that Baldor was Boromir-like in that he also had to be the one to do it.
As for the treasure, I think that is unknown. When Aragorn was gazing at Baldor's remains, before the fast closed stony door he said:
The above was found in the ROTK, Book V, near the end of Chapter 2 entitled 'The Passing of the Grey Company', and also bits were gleaned from Appendix A of ROTK. :read:... Whither does it lead? Why would he pass? None shall ever know!
'For that is not my errand!' he cried, turning back and speaking to the whispering darkness behind. 'Keep your hoards and your secrets hidden in the Accursed Years! Speed only we ask. Let us pass, and then come! I summon you to the Stone of Erech!'