The tortoise did not win the race. The hare lost it. The tortoise is a winner only because his competitor was an idiot — who was complacent and slept off.
There is a take-away in the story. But it is not that “slow and steady wins the race”. It is that “no matter how skillful you are, never underestimate your competitor”, and “if slow and steady could win the race, think what fast and steady can do”.
If the hare had not slept off, the tortoise would not have been celebrated. Slow and steady wins the race only when fast and steady isn’t around.