[oaabzyay] Rat Park seems less fun

Assuming true, Rat Park is both unsurprising and surprising:

It is unsurprising because it seems obvious socialization and the availability of other entertainment affect addiction.

But it is surprising because socialization and alternative entertainment probably don't provide anything close to the intense high that heroin can provide (though not sure what dosages the rats were provided or whether that statement is true for rats).  It would seem that rats ought to still crave the thing that's better even with other things available.  Why not?