From what I've learned so far, there are three types. PoW coins, PoS coins and DAG coins.
I don't think any of them will replace Bitcoin, since it is the most decentralized, and it gets better every day. However, I can see cryptocurrencies having success as complementary currencies, since they bring innovation that are very hard to be implemented in Bitcoin itself.

First, you need to answer: when do you want to become a Bitcoin millionaire?

If it is in a year or so, you will surely need a few tens of it. However, as time passes, if the price of Bitcoin continues to rise, you will need much less than that.

It would be very different. A world without google, wikipedia and so many means of communication that make our lives easier. Getting information would be a real challenge, we would have to spend a lot of time reading piles of books to find information that today we can get with a few key words and a few clicks.

What kind of question is this? Everything that goes up, goes down... not matter the stock or asset you are investing in. The question is, how low it can go?
I think we will be seeing a correction before the end of the year, and something in the order of 35% to 45% is a possibility to be considered.

I consider Bitcoin to be a great investment if you are a long term holder. But I would not recommend you to buy if you are expecting to see your money to double in the next two months or something. I think even these altcoins you mention could not give you that kind of return at this point.

It is said that 1 Bitcoin can make you a millionaire someday in the future, but I guess this future is more than a decade from now, not a week.

Bitcoin is the cryptocurrency with greatest liquidity and trading volume, and the trading pair BTC/USD is probably the best option. But you can also take greater risks investing in altcoins with high trading volume, the problem is that none of them have decent liquidity.

I see no reason to invest in a cryptocurrency that is centralized, and also lacks a good development team.
I think it's worth much more to invest in Bitcoin, especially at such prices.

Right now the industry needs decentralized exchanges, so that people in countries like China would have no problems when trying to trade.

It would not be wise to invest 10 million dollars in altcoins, because there is not enough liquidity. Even if the currency rises in price, the lack of liquidity would bring you problems when trying to cash out.

I don't think so, since anonymous cryptocurrencies would not prevent exchanges from being shut down.

What would gain more adoption would be an anonymous, decentralized exchange.

It would help the price a lot. But nobody in their right mind would buy $40 million worth of Bitcoin at once.
A conscious investor would buy this over the course of a week, or over the course of several weeks.

I've been speculating that the floor is around $3200, and looking at the chart right now, it's close. Not sure if it will hold, but it's definitely too late to open a short position.

And tomorrow Bitcoin pumps. If not tomorrow, it's very lileky that we will be seeing a price recovery before the end of the week.

If it goes below $3000, you can be sure we might not need whales to recover the price. People would be more than happy to buy at 40% discount.

Being 2020 the year of the next halving, it doesn't sound unreasonable.

Hopefully your friend have more good news from the future.

Maybe not yet faster and cheaper, but definitely safer. And more than that: permissionless, borderless and censorship resistant.

If you find an investment with as much potential as Bitcoin, I'm listening... I mean, of course there are some very undervalued assets out there that could outperform Bitcoin, but in the fintech industry, I think there is nothing better.

It is the responsibility of each to educate oneself. But from an investor perspective, we would be helping ourselves by helping other people to come to crypto.

You're right in this one... This is a more precise description of the facts. Anyway, it was a show of little confidence in Bitcoin.