Do you think you can be profitable over time from Manila trading

Hello to trading Community

I have a pretty weird question for most of you, from analyzing the information about the most successful trading firms on earth, like Renaissance (rentec.com), Citadel (citadel.com), Susquehanna (sig.com), etc. First: they never traded manually; second: they are using an army of PHDs that building their trading algorithms. And those firms jointly compound more than 80% of the global trading volume. So my question is, do you believe that you can make your trading profitable while you still trading manually? In my opinion, it's almost impossible, and the reasons are:

1. Long learning curve - it will take a lot of time to master "the market," tools and common strategies. In most cases, you will lose a lot of money during this learning process.
2. Finding your alpha - You can't just take the people's strategies and trade. The most popular strategies that you will find out there are don't going to work for you.
3. Trading Behavior - It very hard to cut looses. To be able to trade without emotions you need to spent years in trading and even then it'll be a big problem.
4. Data - your strategy needs to be updated frequently to take into consideration the last trading information (previous trading week, day, hour) to be able to provide a competitive strategy.
5. Time - Successful trader wants to catch all the possible trades in different exchanges in Europe, US, and Asia but it means you need to be awake 24/7
6. Assets - How you are choosing your assets? Do you trade just stocks that you already know, like Apple or Google? If answer is yes, You are losing the most attractive opportunities and assets to trade. Once you have a trading methodology (your alpha), you need to find all the assets among different asset classes (like Commodities, Forex, Crypto, etc.) that your way to trade can yield significant Updike to your portfolio.
7. Diversification - you can't trade just one asset class from one region, in case this asset class will suffer from a long down trend you can find your self in a big "financial" problem. You need to trade multiple asset classes and regions to protect your portfolio.

I'm a professional trader that always built a trading strategy, and I wonder why people still trading manually?

What is your way to trade?