No you don't get it.
We guess at WAYYYY more than that.
And we only can see what we with our knowledge of lenses, and light can see.
What if the reason black holes seem real, is simply we haven't ever looked at light from the right perspective to see that far, or stuff like that.
We see light doing things, that doesn't make ANY of it true.
It makes it plausible.
And with that I AGREE. It is plausible. NOT true, yet.
You have zero concept of what astronomers "guess" at, and you have no basis for making that comment. It's pure... I'd say
rhetoric, but rhetoric is usually at least somewhat persuasive, your argument is not.
If we have to come up with some whacky explanation like "we haven't ever looked at light from the right perspective to see that far, or stuff like that", you're probably getting further from the truth.
You're right, just because we see it happening doesn't necessarily make it true, but using that same analogy how can you be sure what you're typing is true? You see it, but it doesn't mean it's true; just plausible that you typed it. If we used that inane line of reasoning for day to day life we'd live in a cluster fuck, if we were living at all.
So, we actually see the blackness of a black hole and the rim of light around the event horizon.
We can test and measure very exact phenomenon associated with black holes, e.g. Gravitational Lensing, etc.
We can use mathematics that have been proven to be accurate through testing on earth (that we can observe) to predict where back holes are with near perfect accuracy.
We can observe gasses and other matter being pulled towards large gravitational forces.
Stephen Hawking predicted radiation dubbed Hawking radiation would be emitted from Black Holes; scientists created a "white hole" in a laboratory, and have actually observed Hawking radiation, first person.
But black holes are fiction...