There can be multiple valid folds, the most famous ones are prions which are a different fold of an protein than the native one. The explanation why proteins t

There can be multiple valid folds, the most famous ones are prions which are a different fold of an protein than the native one. The explanation why proteins typically only adopt one fold is not in the process of folding itself. But misfolding is really problematic for the cell, and there are various mechanisms to manage it. A misfolded protein is at best useless, and as you can see with prions can also be actively harmful. The cell has chaperones that help proteins fold, and it has quality control mechanisms that try to remove misfolded proteins before they are released into the cell. But one major factor is evolution, proteins that fold reliably are selected over proteins that can fold into unproductive or harmful conformations. So the proteins we tend to look at already have been selected for their folding properties to some extent.