> Who do you think enforces property rights?
I assume that you intended this as a rhetorical question, but the answer is not "the government". Governments do not exist to defend property rights—that is merely propaganda. No criminal organization violates property rights more brazenly or systematically than governments do on a routine basis. Every tax, every regulation, every disproportionate punishment, every victim prevented from pursuing justice while those ostensibly granted that role do nothing—almost everything the government does involves violating property rights in some form. The only point in their favor is that, like any other protection racket, they are jealous of their monopoly and not very tolerant of lesser criminals setting up operations on their turf.
> And by what basis do they lay claim to make other people respect those rights?
There is no need to "make" other people respect anything. That is what makes property a natural right; the very act of violating a property right naturally justifies a proportional response in kind. That is simple universality and reciprocation at work, the basis for any self-consistent system of rights, and it is more than sufficient to ensure that most individuals will respect others' property rights without being coerced, because they in turn need others to recognize their claims to property as valid. Those who chose otherwise cannot rationally object if their victims respond in kind, taking back their own property plus a proportional amount as retribution.
If you are interested in further reading on this subject, I can recommend Stephen Kinsella's "Punishment and Proportionality: the Estoppel Approach" (https://mises-media.s3.amazonaws.com/12_1_3_0.pdf?file=1&typ...).