This is a sea change akin to the discovery of double-entry bookkeeping or the common stock corporation. You may reside in one jurisdiction your entire life, but the whole point of the internet is to connect humanity. You have no doubt interacted with hundreds or thousands of people in your lifetime online that reside in other states or countries than yourself.

If you want to coordinate with people across jurisdictions to create a venture or a charity or a political movement or a software start up or a video game project or create an artistic franchise, traditionally you need a pre-established relationship to do so. Because one person ultimately has to be in charge of finances if capital is involved. This creates a touchy situation. What happens if your partner in China or Argentina or Zimbabwe wants to custody the funds? You need to not only trust the person to be the treasurer and not run off with the money, but also the local banking laws and rules guarding those bank accounts. This makes coordination across distances difficult and unpredictable and fraught with risk.

Contrast that with placing those funds in a multisig, where you and your 3 teammates (from 3 different countries) all must sign-off on every expenditure from that multisig smart contract. Maybe you're ok with 3 out of 4 signing off on expenditures, that's fully customizable, since it's all code. You can also effortlessly swap between different currency pairs, whether that be Ether, or Bitcoin, or USDC, or Japanese Yen, and reinvest the treasury into yield generating strategies (since there is demand for on-chain loans and there does exist permissionless 24/7 on-chain money markets).

Now, don't lose sight of the big picture, because there's 7-8 billion human beings on this planet, and currently it is nearly impossible to coordinate, raise, and manage capital in a meaningful way for the vast majority of these humans. This is unlocking the capital availability of Silicon Valley for the whole world.

This is such a concern levied against cryptocurrency; why does no one levy the same concern against traditional publicly traded companies? That someone who is rich and powerful enough could simply take control of Apple, or Walmart (assuming they make >50% of their outstanding shares available for trade on the public markets, which some public companies do)?

The reality is: It is a concern. But its a vanishingly small one. To do so would be, in many cases, suicide; and it would be even more-so with cryptocurrencies. It would take an obscene amount of money and resources, converted into assets which held value under the societal context of the status quo. The status quo doesn't like changing; the assets would probably lose all their value as everyone in the 49% abandons their investment. What would this hostile takeover gain? A few billion in revenue? They'd lose far more in the attempt.

For most newer cryptocurrencies (not Bitcoin), this attack is not a matter of owning 51% of the mining power, but rather 51% of the currency itself (proof of stake). To do so, for any reasonably successful and valuable currency, would be crazy. Its just not a concern, period.

It may be worth elucidating this, but: bitcoin is on the way out. The crypto community has absolutely striated into two groups; the bitcoin traditionalists who build ten acre data centers next to volcanos to farm their digital gold, and those more forward thinking who are actually interested in solving the bigger, more tactile problems with cryptocurrency like real use cases, environmental impact, etc. So, many of the concerns surrounding bitcoin, which evolved in the '10s when it was the fastest growing player on the block, are simply no longer relevant.

[1] https://www.bloomberg.com/news/features/2018-05-17/china-s-c...