I could simply try to insult you or make a sly remark regarding a correlation between SLI/Crossfire and having a small penis, but instead I'll write a (fairly) serious rhetorical response.
This is simply not true. Firstly, this assumes that you have a high-end multi-GPU setup, as any multi-GPU setup that can be matched in performance by a single-GPU setup would negate the status of the former as an 'enthusiast' solution, as an inherently 'non-enthusiast' solution could offer the same caliber of performance (again, regarding multi-GPU cards as multi-GPU solutions). So labeling any SLI/Crossfire setup as an enthusiast setup actually contradicts the label itself. Further, the situation of having a single card then adding another one months later would not make you any more of an enthusiast than someone who will simply keep a single high-end card. The only situation left is someone who spends a lot of money on multiple high-end cards, in which case you simply have a lot of money and/or a lot of time to put towards playing games. This doesn't necessarily make you more or less of an enthusiast than someone who doesn't have copious amounts of time and/or money, but, then again, if your life revolves solely around your computer, then I suppose it does. So yes, if you consistently have a multi-GPU setup consisting of high-end GPUs, I suppose you would be more of an enthusiast than people who would be running a multi-GPU setup based on older tech or, god forbid, has "only" a single high-end GPU.