Airdrop is considerable a time wasting over a hundred of airdrops you participated? Maybe 1 or 5 airdrops are guaranteed for you to pay. Airdrop payments are ranging $1 - $5 also so and this is not a good way to earn crypto currency or Bitcoin.
Everyone has their own understanding of the waste of time. For someone who sits all day at home and does not know what to do, such a time spent may well be useful, even if he earns a mere penny.
It all depends on your standard of living and your wealth. For the most part, you can find a more effective application of the time that people spend participating in countless airdrops, but not everyone wants to be effective. Some people just want to do nothing and get paid.