No there are other options to earn bitcoin without spending any amount. And that are joining some free airdrops although this is not 100% sure that you can earn but at least you have a chance to gain for free if there is a legitimate platform will pay to its early bird users.
Yes theres an airdrop of bitcoin here? But I did mentioned some raffles. Most airdrops are earned in altcoins well if they earned those tokens they could trade that into stables and convert to bitcoin. Im sure some are doing this like me. Can you share some airdrops of bitcoin you said? Aside from the 2009 or 2010 free bitcoin like before when downloading their software. Surely OP talks about the time now.
Joining on that doesn't mean you can earn bitcoin directly, the main point on that word is he can possibly earn what those devs give to him and convert it to bitcoin. This is common thing people do since we know airdrop earners exchange those token to bitcoin so that they can withdraw. So for OP and other newbies case they can use what they earn to invest on other bitcoin investment schemes or they can trade it back again to multiply their earnings.