The census I technically a good thing, in my opinion. As long as the tax money gets distributed how it’s supposed to, I’m fine with it.
Also, they can’t use information from any other government database. Use tax forms? I know several people that work under the table, so they wouldn’t be counted. It takes two minutes to fill the thing out, might as well do it. Plus, since you paid for the census to be mailed to you, and the postage to send it back, you might as well fill it out.