This is very misleading. Most of the discomfort would be from the hard table against the back of your hand, and this would be because of local pressure on specific points.
Pressure causes problems when there's a big change in a relatively short time. Ears, for example, have a hard time with this, but you can equalize them by closing your nose and mouth and trying to blow out. Before I knew about this trick, I could never dive to the bottom of the pool. Now, no problem.
A more realistic example would be to bury your hand in a foot or two of fine sand. Does that sound uncomfortable?
In the sand example, it's also important that the pressure is acting from all sides (top, bottom, left, right) so there's no force acting to deform your hand.
We can handle a relatively large range of pressures, and there are other problems before you start causing mechanical damage from the actual pressure (lack of oxygen at low pressure, dissolved gas at high pressure).
edit: grammar
This is very misleading. Most of the discomfort would be from the hard table against the back of your hand, and this would be because of local pressure on specific points.
Good point, but it feels about as uncomfortable if you use a padding over the table that eliminates the stress concentrations at your bones and knuckles. Especially if you double the dumbbell weight and recognize that it's only a pressure increase of 10%.
There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.
Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.