Perhaps this is why my younger brother is a part-time slave to his drink... He's never quite crossed that line - probably because our parents live with him. But being the youngest has both advantages and disadvantages - advantages that you get away with more and enjoy more solo-child time when the older siblings have left... disadvantages that the parents have less time/energy to focus on your wants and needs and are busy with other things when you get to that only-child stage at the other end... Yeah, he definitely felt neglected regardless of whether that was truly the case, but with his Gemini sun and moon... he's never had to grow up away from his "evil twin", so his evil twin can also steal time and limelight from his sun. It's hard to watch - thankfully, I at least have distance when I need it.
That is right. Some parents would think the elder siblings will help in raising the younger ones but they forget that the elder ones have their lives to live. You only get to enjoy it (being the youngest) when everyone is still around but after that stage, you have a lot of work to do to keep yourself running well.
I had to help a lot with my younger brothers. More than what is generally required these days - and I didn't have the tools either. But it still did me good - and hopefully they have forgiven me being the bossy older sister! However, as you said, older siblings finish growing up and leave the home. My youngest brother was 12 when I left home. Seems sad to have missed out on his teenage years.