Well yes, obviously gay people and drug users are not the bulk of the population so that 32% indicates 32% of all of those that end up HIV positive.
For the mainstream population that is a much lower risk than for a smaller group that has a roughly equal incidence in absolute numbers.
But that risk is still substantial, and you do not want to end up as an entry in the tally of that 32%, which is a substantial number of individuals, if approximately 4% is LGBT then maybe 50% of those (so 2% of the population) takes 68% of the cases, leaving 98% to divide the remaining 32%.
There are many lotteries with far fewer winners.
That's not how statistics work.
MSM and IV drug users are a small percent of the overall population. If you looked at the rate of HIV cases and divided by the respective population, you'd see that MSM and IV drug users are at a far greater risk of contracting HIV than heterosexuals (by magnitudes of order).
However, that certainly doesn't infer that heterosexual can't get AIDS and that they shouldn't seek to avoid it through appropriate measures.