Some key points about ethereum

I have been following ethereum for a couple of months. I do not claim myself as an expert but I'm still loving the concept and involving myself developing decentralized applications on this platform. Today I noticed a key factor in this altcoin. If you notice closely you'll see that ethereum has no maximum supply. I might be wrong but I suppose they can supply the number of coins. Which seems very suspicious. The core developers of ethereum seem to make it as a monopoly? If you try to deploy a code or smart contract for executing every line of code it costs gas or a fraction of ETH. I was thinking of making some applications but I wonder how many people would use it as it actually costs a lot more than traditional applications. And if there's no maximum supply how the deflation will ever occur like bitcoin? If you know more about it please comment below some links so that I can understand more. Is it worth to invest into this cryptocurrency as a long term investment?

Thanks in advance for reading the posts and helping me understanding it deeper.