I am tall and fat challenged. I have often ridden inexpensive mountain bikes. I do break bikes. The most common thing to break is the spokes in the back wheel. It may take two years or more of riding on rough tracks. Then one spoke breaks. It is normally not until riding several more times that another spoke breaks. Then it becomes time to replace the back wheel.
You are unlikely to have several spokes break on one ride. You can normally always side home.