It depends how you define gambling.
If you consider that it means risking money on an uncertain result, then yes it is.
Yes, but if I bet a fiver on a horse, I am controlling my risk as the most that I can lose on that bet is a fiver.
If I have 500 in my pocket, I am only risking 1%. The only slippage with horse racing is if the turf is a bit muddy :)