But what's the poooiint..
Here are a couple of my favourite songs that I think put it well:
https://m.youtube.com/watch?v=OvMoRVrqx_I
http://www.dailymotion.com/video/x2z46va
Here's one of my favourite stories about the same thing:
https://www.brainpickings.org/2014/02/25/margaret-mead-meani...
Sometimes it can be fun/stimulating to consider the nature of existence, but if it isn't taking you to that place, why do it? I half remember a story about a famous mathematician who drove himself mad trying to solve a problem regarding infinities, to me this is a great example of the difference between intellect and wisdom. If you're driven to understand something, I'd suggest that tells you something that's interesting in its own right, so to turn it back on you, why do you want to know?
With the example of the mathematician, you can read it a number of different ways, but one of the things I took from it was the difference between a healthy curiosity and an unhealthy curiosity. It sounds to me that you have a healthy curiosity, and enjoy the mental stimulation of exploring the big questions. As long as it remains something you enjoy and you're still open to enjoying other things then you can't really go wrong. If you'd like to find kindred spirits that also enjoy thinking about the big questions, you can find plenty in the world of philosophy. I can recommend The School of Life as an enjoyable way to explore philosophy. As some examples, here are a couple of my favourites from TSoL:
Learning can be done for your own enjoyment, but what I would suggest is the mindset that many of us used to get us through school isn't likely to help with that. I think this video puts it well:
Related to this, here's a discussion about deschooling you may find interesting:
One last thing...
Best of luck!
Whilst I can see that you're looking into nihilism, it's worth knowing that nihilism isn't the only alternative to conventional views and religious dogma. To start this exploration, let's look at reincarnation. My favourite way to look at this is... If you eat an apple, has that apple been reincarnated as a human?
If you want to leave, you're free to go.
The planet isn't random, it is one that can sustain life in our form. That we don't know everything about our existence, that we have to piece it together as best we can, and share our findings with the next generation, is all very exciting and amazing and awesome to me. I guess I am just the type of person who loves open world games :)
Also, it makes me get less upset when I see shitty things in the world - the fact that life that is just evolving to survive can get our shit together as well as humanity has, is frankly pretty amazing and impressive.
You lament that you run into so many people who care about those things, and they are blind to the fragile and fleeting nature of it all, but I am unsure why that is such a horrible thing. Everyone is going to choose their own meaning for their lives, and sure, some will choose things that I don't understand and I don't think are important. But that is their life, and them choosing to care about those things doesn't change your life. You are not bound by their preferences.
In fact, I think it is great that all different people have such varied opinions on what is important. I get to observe them all, and see what life would be like under various scenarios. The human existence is so amazing because we all get to lead our own separate little 'experiments' in how we should live our lives (what we should do, what we should care about), and then we can share with each other what we have learned while trying these things. Some of the experiments will be utter failures, and some will be successes. We can learn from them all.