"Those who say it cannot be done should not interrupt those doing it."
Sometimes I enjoy the nay sayers. They make it ever so rewarding to succeed. If everyone agreed it was possible, it would not be interesting. But when the nay sayers have the power to stop you they become toxic. And as you make progress, which shows the nay sayers were wrong, they truely interrupt. It happens mainly in organisations with heavy politics.
I once worked for a company that wanted to outsource a very complex machining operation and the owner of that company told me it couldn't be done. I professionally told him I have been doing it successfully and trained my guys to do it perfectly. I said "I think you should bring your team down here for a field trip to see this isn't impossible" This was an excellent lesson for this company to think outside the box.