You don't retrieve those particles; an admittedly absurd extension of your reasoning would imply that it takes 200 million years to image a quasar, because that

You don't retrieve those particles; an admittedly absurd extension of your reasoning would imply that it takes 200 million years to image a quasar, because that's how long it takes to retrieve the photons that form your image. What we're seeing here is both faint and enormous. Both characteristics make it hard to detect, and it isn't bright enough to capture without a long exposure, plus you can't look at it during the day, and you can't see the side beyond the sun... all characteristics that lead to longer imaging times.