All of your backers want you to succeed.  They are like customers that actually like you, sort of.  They like what you are showing them and are willing to bet on your ability to pull it off.  Many of your backers are your biggest fans and will cheer you on as you go.  Then, there are a few who either don’t understand your project or for some reason have been put off by your project after backing it and can really bring you down if you let them.  Don’t let them.  Sometimes you will need to gracefully allow a backer to withdraw support.  I suggest doing this through a direct personal message rather than a public post.  Explain to them that you understand their concerns or complaint but can’t fix it right now, lest you upset even more backers.  Let them know you appreciate their backing but understand if they choose to withdraw their backing.