You cannot become a blockchain developer by just taking blockchain courses and if you're still confused about the basic understanding of the blockchain network, then you have a long way to go in becoming a developer. You need to take this courses because you need more understanding about the bitcoin and blockchain network, not because you want to become a developer.

Then at the end of the course, you can grade yourself and the extent of the knowledge you've gained, is it substantial enough, are you really a technical guy that can actually become a developer, you'll make the decision yourself, but the course will impact in you whether you're a developer or not.