Are Airdrops and Bounties really leading to a successful coin? There are so many out there this time.
Or are they mostly shitcoins, disappear or using your emails for phishing?
Have you ever participate to one with high profit? How long was wait for that?
I think most of them are just bullshit and time wasting and not worth putting some effort in.
Regarding your first question, there is no guarantee an airdrop or bounty will lead to a successful coin. It could lead to a successful ICO (in the sense that due to the publicity they reached their hard cap, sold out, etc.), but that won't necessarily affect the success of the project itself. On the contrary it could lower the price of the coin once bounty hunters start dumping their earnings.
However, I do feel like they are useful, especially for people just entering the crypto world who might be unable to actually invest. They can earn their bounty and either hold or trade for more established coins once it hits the exchanges.
As a bounty participant myself I have made some profit and it was worth it (taking into account the time spent).