Combat sports is defined by a consensual, athletic measurement of two or more opponents under the same conditions and rules from which the technique portfolio conveyed in the respective martial art is derived.
However, self-defense situations never arise amicably, nor are there usually factors such as sporting fairness or even equal conditions. Even the active fight against an opponent does not fall into the scope of legally permissible self-defense in most cases.
For these reasons, combat sports of all kinds can only be suitable for self-defense purposes to a very limited extent, but technical elements from them can be used for self-protection.