Since I have personally received (unsolicited) confidential pitch decks from several first and second tier VCs who have taken a pitch from Company/Founder A, al

Since I have personally received (unsolicited) confidential pitch decks from several first and second tier VCs who have taken a pitch from Company/Founder A, all the while entirely committed to funding Company/Founder B, ie sending the deck around to their network to gather feedback solely for the benefit of Founder B...I would say the concern is well founded. That said, I would also say that "ideas" never get funded...only teams/founders get funded. The idea you start with is rarely the idea that makes a business work. Meanwhile, a good founder/team can take practically any flawed idea ...within reason... and make it work as a business.