Unpredictable timing of the bonus round
The 6x6 grid of Gates of Hades is high volatility, and that describes the size of swings, not their timing. How often the bonus round comes is not known in advance. The result of one session is random, whatever the RTP. Two sessions with the same bet can end far apart, and no past spin changes what the next one pays.
Three RTP versions of Gates of Hades exist, and each one carries its own return. Which version this lobby runs is shown only in the game rules. Read those rules before your first spin, so the return you expect matches the version you are playing.
x10,000 is the ceiling of Gates of Hades, measured as a multiple of the bet. Hitting it is very rare, and nothing in a session shows that it is close. Treat the figure as the upper edge of what is possible, not as a target.