That's it, all unethical behavior is suddenly okay if it's legal, and caveat emptor? Contracts have very little meaning if one of the signatories can disappear

That's it, all unethical behavior is suddenly okay if it's legal, and caveat emptor? Contracts have very little meaning if one of the signatories can disappear without holding their end of the bargain and without consequences. Is this the society you want, one where giving someone your word is meaningless?