Bitcoin Forum

Today, I read the most hilarious analogy by a Chinese btc holder.
 "Hypothetically, when President Mao founded the New China in 1949, there were 57 kilos of gold in total that are as fixed as bitcoin. Mao gave one kilo of gold to the 56 ethnic minority groups and embedded the last kilo in the back of a live turtle. 68 years later, China’s GDP reaches over 570 trillion CNY and we are still in the time of gold standard, then one kilo of gold equals to 10 trillion CNY. That turtle who did nothing in the past 68 years now occupies 10 percent of China’s total wealth."
Anyway, his key point is any deflationary bias currencies are inherently speculative.

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

but in his article, he also said in the bitcoin market, it is so clear that when you hold 12 million bitcoins, you control 50% of the whole market and 90% when you have 18 million bitcoins.  His full article is here http://news.8btc.com/the-upper-limit-of-21-million-makes-bitcoin-a-perfect-speculative-tool-instead-of-a-currency

there are only 16.5+ million coins currently available that are mined so far and half of that means 8.25 million not 12 and it is not a question of "when" it is the question of "if you are even able to reach that point". even the richest whales from early years don't have anything above 500,000 and the speculation about how much Satoshi owns is something less than 1 million.
if someone could have that big a share of bitcoin market, the price would never rise this much.

"if everyone just holds bitcoin in their cold storages that is the death of bitcoin in my opinion.", this is exactly what is going on. so many believe btc price would be like "one btc, one house", and they use it as a store of value. and at this point, so many complain about btc transaction fees and switching to alts.