Akira: my Sachtlers have toppled over and fallen to the ground more times than I care to remember, and nothing untoward has ever happened to any of them. I think their multiple-tube design helps a lot in avoiding breakage.
In the 'torture' test, we simulated such toppling incidents and counted how many times the test could be repeated before vital parts broke. Even the better tripods in that test didn't reach 10 times and most were pretty shabby after just a fall or two.
For indoors use, you need the ground spreader or the special "red sox" attachment you so often see on TV. Never had any issue out in the wide open without these auxilaries though, not even on ice. I have these items, of course. Just in case.
Under water, a Sachtler is just fine. It's easy to adjust the leg length too. A pro tripod has to serve when you need it. Putting it into mud, snow, or water is nothing special. Here is a snap of a female TV photographer I helped some years ago when NRK (Norwegian National Broadcasting) made a series from Norwegian RAMSAR sites. You will notice her Sachtler is submerged. Only the camera and part of the tripod head is above the water as the camera is not water-tight. She didn't hesitate a fraction of a second before setting up the tripod in this manner. That is food for thought.