Just save gems and try to not waste it.
Collect up to 50 gems and hatch only in legendary festival .
Don't hatch eggs in festivals in which there is ×10 chance of getting limited legendary.
Hatch only in legendary festival where there is limited packs like the current one.
I was not lucky this time.
But I always hatch eggs in such festivals only
I am playing since 1 year and I have 15 legendaries (including fast strike the starter)
Every time I hatch I get rare gem and after 5 hatchs
I can hatch rare gold gem
This will guarantee help to get legendary
But this time I was unlucky
Because in first time I got 2 legendary but that which I already have and in second time I didn't got any legendary