the argument has never been about "which one is the best"! the argument has always been about pros and cons of each system and bitcoin is preferred over centralized currencies in many cases by many people because of its decentralization and the fact that it will be free of corruption as a currency.

it is not "virtual" it is "digital" there is a big difference between these two words. use a dictionary.
and people aren't afraid of bitcoin because of that, instead they are afraid of it because of its volatility, because of it being new and because of all the FUDs.

Centralized system promotes despotism. Decentralized system allows you to truly control your money.

Decentralization is the best because you are holding the coin of yours but in centralized system someone is controlling your funds so you need to decide which one is best.Most of the people are afraid of bitcoin price because the price is bumping and dumping too often so it can't be used as currency yet.

both of them exist and they don't have to contradict each other. they can both live side by side and each satisfy a different kind of need.

the centralized money is limited to one country, it is tied to its economy for example and it is in the control of the government.
bitcoin as the decentralized currency is global and it is not affected by local laws or economy, etc. and this "nobody controls it" feature is a very good one.

Decentralised currency seems to be much better than centralised currency.Here in decentralised currency,we are free to use it without being monitored by any authorities and not having any limits to send and withdraw.Also,currencies like bitcoin are free from deflation due to their limited supply unlike USD printed infinitely.Also,decentralised currencies could not be devalued by governments like what Indian government did by demonitising high value notes thus shattering the trust of normal people.That's why,people have started to see decentralised currencies as a safe haven.

Decentralized digital money has a number of undeniable advantages. However, as we see, due to the large volatility of the crypto currency, it is rather difficult to use as a means of payment. For this reason, it can not be used as the main means of payment. In addition, since the crypto currency is not provided and is not regulated by the central body, its increase in price, since it is formed exclusively on the basis of the supply-demand ratio,
 clearly shows the nature of it as a financial bubble. In order to preserve the dignity of the crypto currency and eliminate its risks, this decentralized crypto currency should, in my opinion, be moderately regulated by the states.

Absolutely decentralised money bringing a opportunity for you to use your currency as your wish! and you don't need to any explanation for your digital money related activities.  also you can gain more profit from digital money if it's value rising then present.

In as much as decentralized money offers freedom and secured access to your funds it's highly volatile because there is no central control of its inflation like centralized money and so you could go from a million to a zero within a short period of time.

Both have their cons and pros, regarding the decentralised money you will be having full control on your money, your digital currency can't get freeze like banks use to freeze suspected accounts. No need 3rd party interference for your money transaction and this decentralized system is giving freedom to the financial system to anyone. For example, there are many countries in the world consider rural areas who don't have access to banking system or can't afford the high fees implemented by banks, for these people adopting decentralized system is best. But one more thing if you lose your digital currency you can't claim to anyone for reverse transaction or funds lost due to revealing your PK by mistake.
Let's come to centralized system i.e. banks, they have control on your transactions if hacking takes place on their servers or ATM and your money is stolen then banks will reimburse you for your lose unlike in decentralized as there is no authority controlling decentralized system.
People must adopt any means of financial service as per their needs.
And obviously financial analyst will advise you to put money in banks, don't they want to make profits from our money?