Mainak is golden mountain,Hanuman was on a trail for Lord's order.If you are on a spiritual trail ,taking every step as Lord's order and his work,worldly happiness and material benefits(gold etc) comes in abundance to you all by itself.
Mainak served Hanuman and hence got his grace , in return he also got grace of Indra who let him stay in the ocean with wings intact. Tose who have Hanuman's grace ,they automatically get other dieties' grace too.
Without wasting time over Mainak,Hanuman went ahead on his mission.Those on a spiritual path to attain glory and Lord's blessings ,one should stop dwelling on gold and other wealth.
Hanuman never tires or exhausts , here he was on a short mission.Everyday in every living being he is present to facilitate breathing, others have atleast some rest in sleep ,but even in sleep Lord vayu keeps working for the soul , else none would get up from sleep. Thus from birth till death Lord Hanuman protects all living beings ,hence he is Jeevottama.