gold is not bitcoin, in fact they have nothing in common!
gold is getting its value from so many different usages it has. from obvious things such as being used as a jewelry to small things such as usage in electronics, and other parts of science as an element. and so on. so it doesn't matter if one idiot held 1 kilo of gold, the rest of the world were still using gold as it was meant to

bitcoin gets its value from being decentralized secure and also for being a currency and for that to succeed people need to use it as a currency, if everyone just holds bitcoin in their cold storages that is the death of bitcoin in my opinion.

the turtle is gonna fall over and die!

to respond to the OP title...
"The upper limit of makes bitcoin a speculative tool instead of a currency"

not really.
the exchanges make it speculative.
for instance code could be added so that bitcoins 'price' is fixed to things like the cost of living index. and the variation changes at a predictable timescale of deflation.

this is known as 'pegging'.

so its not the 21m cap that causes speculation. its the lack of code/rules of trade, lack off fee priority formuleas to ensure healthy utility that causes the speculation

its the lack of rules lack of information, lack of future knowledge that causes people to guess

guess=speculation

Bitcoin will never become a 100% global currency, so just forget that. This pipe dream of Bitcoin becoming a global currency, is impossible. People and countries cannot even come together on things like climate change and cultural differences, so why would they accept Bitcoin as a reserve currency?

80/20 will be with us, as long as there are capitalist systems in this world. ^hmmmmm^

i keep seeing articles from 8btc repeating the same thing for some time now. it is like the 10th article that i see in which they quote some people we have never heard of who are calling bitcoin a pure investment and nothing more.

and each time i will repeat: "Bullshit"!

bitcoin is a currency and if anyone wants it to thrive, they must accept it as a currency. otherwise we are just wasting our time speculating to no end.
and price can not go higher than a certain level unless it is for real adoption of bitcoin as a currency.

people seem to have forgotten why this rally started and why we are $1000 above the previous price! in which case it is because of Japan and their adoption of bitcoin as a legal method of payment aka as a currency.

In my perspective first it will lower the worlds economy because most of the money returns and come in the web. And businesses would run out of workers because opportunity in btc is more easier. Bit by bit more and more businesses are investing in in btc and i think most money would go in the web and most oppurtunities now underlies in btc. And local goods wont have any rich business men to invest in them or fund them.

i couldn't agree more.
these days 8btc seems to be publishing a lot of these low value articles about so called "investors" who are repeating practically the same thing about bitcoin and call it an investment which is not good!
and apparently none of them even know that bitcoin is a currency first then an investment. specially these days that big countries are adopting it as a currency, not calling it as an investment.

Why is it always chinese? Where does 8btc find this people?
I agree with the part that you can't get out in the world of crypto currency
it's like a whole new world to be discovered and earn this digital currency in many ways
Before you know it you're addicted to it.

Trading crypto is quite hard job as even a small piece of news/fud/hype can trigger massive market move which can't be predicted earlier to make safe exit. For example, bitcoin price pumped over 10% overnight today while all alts are red without any news/update.