A monero address includes a 32 bit checksum, so assuming the checksum is randomly distributed over the whole space, you get one match over about 4 billion, or 0.000000023283% chance of the checksum matching by pure chance.
However, all 95 character strings do not represent a valid address in the first place, so a failure to decode as base58 will also get an invalid address rejected.
If the address is invalid, you don't lose your monero, it just doesn't get sent. If it's a valid address to which you do not have the private keys (or do not know who does, or that person/entity is not willing to send back), then you do lose your monero.