user47935: From my understanding, Bitcoin is decentralized and not controlled by any company or organization (so, for example, no bank is behind Bitcoin).
However, this seems to not be powerful enough to resist to the country laws.
There are quite a few countries where Bitcoin is illegal, for example, Bangladesh:

In September 2014, Bangladesh Bank said that "anybody caught using the virtual currency could be jailed under the country's strict anti-money laundering laws"

So, why is the fact that Bitcoin is not controlled by governments/organizations/banks/etc so important, if the government can actually say don't use Bitcoin and it becomes illegal?
As one who has bitcoins, what should I do if my country will Bitcoin one day?

user48509: Well this is a vague question.
To answer your query from the county's government context:
Any form of payments that surpasses their way of handling the payments will surely attract some potential threat of being called as an Illegal asset for the citizens of that country.
The use case of Bitcoins have started and grown in such aspects that no one is so sure and so unsure for and when they are being used.
Thin line difference between "declared as Illegal" and "stop using Bitcoin" statutory warnings.
When Illegal : Keep it as a converted currency in fiat format(USD,CAD,INR etc) or some other Non illegal declared cryptocurrency being used on the Internet.
When just a warning/public announcement : Keep watch on the National news and continue minimalized form of trading .

user25114: A party can send a hexadecimal string to another party and nobody in the world can prove bitcoin or any form of money was sent. Governments can ban bitcoin usage but the bitcoin protocol is indistinguishable and can be implemented using plain speech, so it would be a matter of banning freedom of speech.

47935: <p>From my understanding, Bitcoin is decentralized and not controlled by any company or organization (so, for example, no <em>bank</em> is behind Bitcoin).</p>

<p>However, this seems to not be powerful enough to resist to the country laws.</p>

<p>There are <a href="https://en.wikipedia.org/wiki/Legality_of_bitcoin_by_country#Summary_by_country" rel="noreferrer">quite a few countries</a> where Bitcoin is illegal, for example, Bangladesh:</p>

<blockquote>
  <p>In September 2014, Bangladesh Bank said that "anybody caught using the virtual currency could be jailed under the country's strict anti-money laundering laws"</p>
</blockquote>

<p>So, why is the fact that Bitcoin is not controlled by governments/organizations/banks/etc so important, if the government can actually say <em>don't use Bitcoin</em> and it becomes illegal?</p>

<p>As one who has bitcoins, what should I do if my country will Bitcoin one day?</p>
 48509: <p>Well this is a vague question.
To answer your query from the county's government context:
Any form of payments that surpasses their way of handling the payments will surely attract some potential threat of being called as an <strong><em>Illegal asset</em></strong> for the citizens of that country.</p>

<p>The use case of Bitcoins have started and grown in such aspects that no one is so sure and so unsure for and when they are being used.
Thin line difference between "declared as Illegal" and "stop using Bitcoin" statutory warnings.</p>

<p>When Illegal : Keep it as a converted currency in fiat format(USD,CAD,INR etc) or some other <em>Non illegal declared</em> cryptocurrency being used on the Internet.</p>

<p>When just a warning/public announcement : Keep watch on the National news and continue minimalized form of trading .</p>
 25114: <p>A party can send a hexadecimal string to another party and nobody in the world can prove bitcoin or any form of money was sent. Governments can ban bitcoin usage but the bitcoin protocol is indistinguishable and can be implemented using plain speech, so it would be a matter of banning freedom of speech.</p>
