I've joined the airdrop over the past 3 months and I only get very little value from the airdrop, the majority of which I have to keep it to add value.
So how can I earn a few hundred dollars a month if the bounty is a good plan?

Don't be greedy by continuing to follow the airdrop, you have to pause the time for airdrop so that it is not considered spamming. Working naturally will be better and can be appreciated, you already know the tricks to get airdrop, so you will keep trying to get it, and your success is good and tempting.