Seems all your questions has been answered here so before you lock the thread (which you should do right away), I just want to throw in my 2 cents. Obviously the cash is one of the reasons majority are picking interest in these new trend. You should be very cautious though as there are a lot of scams out there. Be very skeptical as 99.9% of the current project parading themselves as DeFi are just copycat or pure scams and are likely to die within a short time span.
Take it from someone that has made some decent amount of profit from these new trend and also have lost huge amount of money that if that profit would had been secured in Bitcoin, the story would had be different. You chasing after the hype might just end badly for you. You can go for the technology but don't be decieve with the ROI they're shilling the project to give. Borrowing a phrase I saw on crypto twitter but can't recall to quote the source', it goes like this,
Bitcoin sneezes (-5%), DeFi altcoins catches coronavirus (-30%+).
keep that in mind always.
Since you're new to the space (judging from your words), the best you can do for yourself is to concentrate more on studying and understanding Bitcoin. Sure you can get some ideas on other blockchain and developments but don't let that distract you.