Help me invest ~100 euros

Heyyo!

　After summer and everything I got some money left, not really planning on buying anything, well maybe a phone. I'm a person that saves money, so I wouldn't want to do anything crazy, I thought about some options and I came to a conclusion that I am ready to 'donate' 100 euros on trying to get more. I thought I could maybe invest in BTC or some other cryptocurrency, really considering on investing in BTC since it's price is rocketing up. It all seems cool and easy, but I don't really know how and where to do that - like invest in stocks or just load up a wallet, and if, then where? : D
　I also thought about maybe buying a phone for some 300, 400 euros and then refunding it, but that's not really what I'd like to do cuz yeah, It'd be cool if I got a new phone, but it isn't really necessary for me to get a new one right now, and also it seems for me that refunding phones is usually hard and often ends up non-successful.
　I also thought about reselling stuff, cuz I'm pretty good at that. I'm currently searching for stuff that has hight resell value. I'm currently making some money doing this too.
　As some might know, I have opened a Spotify service and am working on support as much as I can, so don't call me a lazy fuck who wants easy money or something like that ;d.

Please post your recommendations below.
And as always - if you don't have anything logical to say, don't say it - don't shitpost!
Thanks!

I'm 15, why does that matter?

Mkay, but which wallet would you recommend? I have a Blockchain wallet, but they have high fees compared to conbase and others, as I know.

I recently found out about WireX, I think they're what you recommended for me to use. If not, can you tell me what you mean by a trading platform or even give me a specific name of one you would recommend!

Oof, I can deposit with cash in my coutry, the cheapest one would be for 1.05% more than the accual price, is that good or bad? ;d Also they accept from 100 to 7,2k euro, so that would work perfectly for me.. I'm starting to wonder - where and how would I sell them at? Sorry, I'm still a noob at this

You can sell them to coin base, local bitcoins, eBay, or even here

Aight, I'll definitely look into this deeper. And selling here.. - uhh I've heard that people are getting refunded..

100 euros in bitcoins? seriously, and how much will you get? with an increase of x2 200 euros? lol

Honestly you need more than just 100 to make a good investment. At that amount the returns aren't very good. I would try to save a bit more, maybe offer some services to make more money and then invest when you have a more ideal amount.

Aight, how much would you recommend for me to invest then?

that would feel a profit, at least 10k

What, are you suggesting me to rob a fucking bank? Where'd I, usual 15yo get 10k? Dude, use some common sense