Yes, we do exist. 70 million of us exist.
Probably more— Bogaert’s original study found more like 1.05%, I think, and I think also gave reasons why the number was likely to be underestimated than overestimated. I can’t remember what they were off the top of my head, though.
As I recall, he suggested that people who weren’t straight were less likely to fill out the survey and respond—that’s a pretty common sampling issue, especially for sensitive topics. People who are afraid of being judged are much less likely to answer things, and people who are generally not sexually active/who don’t think sex is important are also unlikely to answer a survey on sexuality. If I’m remembering right, there was an unusually low proportion of LGB people responding on that survey, too.