Sure, if thousands of years is a long time.
If a civilization stays around their star I would agree with your analysis. But I see no reason to think that no members of an advanced civilization would be interested in going elsewhere. You need enough people to support a technological civilization at your destination, or you need machines capable of removing the need for covering all needed fields of knowledge. And note that if upload becomes possible (and why wouldn't it?) you get a situation where the equipment goes by slowboat but the people move at lightspeed. All it takes is one tiny subset of one species and the galaxy teems with advanced race(s).
And it seems that the physical constraints of sheer distance mean that they will.
I am interested in going to the Moon. But I can't. Nobody can. Well, a dozen people did; But that was a massive undertaking, just to travel a paltry 1.3 light seconds.
None of which exists. Or is likely to.
Why would it?
Sure. But even for just that one, it needs to be achievable.
There hasn't been time for a K2 civilisation to arise within a short range of us. We have only made it to about K0.75 on Sagan's adjusted scale, and there seems little need for much more growth, particularly as human population has essentially peaked.
Sure. But we couldn't detect our own civilisation right now, from just a few tens of lightyears away - and there wasn't any such civilisation to detect from any further away than that.
80 years ago nobody had been in space. Now tourists go. Things become easier over time.
I find your ideas on what technology can do very pessimistic. And yet you are extremely optimistic about the possibility of survival if things go wrong.
Why wouldn't it? Even if we never truly understand how the human mind works we can emulate the hardware. Might cost 100x on the performance but that puts it in Apollo range (remember, the human brain is highly parallel, thus it can be emulated by a bunch of computers in parallel.) That means the only true limitation is performing an adequate read to load the emulator with and I find it hard to believe that would be impossible given extreme pressure + extreme cold (keep the ice crystals from expanding and doing damage) followed by ablating away the material to read what's underneath. This is of course destructive and the first cases would be hail mary's--but someone near death for reasons that do not involve the brain very well might be willing to take the chance once it had been demonstrated on animals.
A craft that is mostly lightsail and using current production techniques can do about 1% of lightspeed, you can add a bit with lasers to overcome drag losses but you'll need to arrive with only .01c for a sunlike star unless there's a laser there to slow you down.
Short intergalactic range. Like Andromeda.
Someone carefully looking could find us at tens of light years. Earth is far too noisy in the radio spectrum, you don't need to be able to decode individual transmissions, just note the presence of excess energy in specific frequency bands. While there might be a natural source of radio energy it's not going to exhibit the sharp frequency edges of Earth. (Frequencies used for radar, especially military radars.)
Billionaire tourists, who don't care about the fact that "space" just means "above the Karman Line", and is barely "space" at all. 12 people have visited another celestial body, none since 1972, none "tourists" of any kind.
Can it? Or will it be torn to shreds by micrometeorites within a few million km?
Sure. What happened to "Short intergalactic range. Like Andromeda"?
Or else there is not a single Great Filter but several filters, behind us in time, at us in time, and ahead of us in time.
I currently have no reason to believe that this kind of technology wouldn’t simply kill me and make a copy who thinks it is me. But “I” would be dead.
Largest and heaviest animals largest masses (all present day unless stated otherwise):