Firstly, there are some airdrops that require bridging and many other stuff that also require fees, which means some of our crypto will be used on fees and coins that get bridged. I do have to warn you that do not rely on this all the time, cos if you are newbie, you won't know that airdrop will be worth it or not.
A newbie could easily fall for scam airdrop more than one who is not a newbie. The general concept of airdrop is to reward users who have helped in building their projects and contribute towards the community through social media tasks or test nets. You don’t have to give a penny to be rewarded for an airdrop and for those airdrop that requires to give out some money (retroactive airdrops) are most times worth it but still it’s not a financial advise or go ahead when you see one. Nothing is guaranteed on this space, you just have to do your own research and only invest into what is worthwhile and can give you higher returns. Airdrops use to be a very good way to earn a lot of money in the past when cryptocurrency where still in their early stages, but now a lot of scam projects have taken over the space and you need to be careful not to fall scam to any in the name of airdrops or some other juicy offers.