I am yet to fully understand how the bitcoin or any crypto, works entierly and if someone does not mind helping me clear a few thoughts that cross my mind.
if there's only 21 million bitcoins to be mined by year 2100+ , why is that the majority have already been mined in such a short amount of time,
Because that is the way Satoshi set it up.
Bitcoin is designed so that a block gets create on average about once every 10 minutes. In the beginning it was set up so that each block created 50 bitcoins. That continued for 210,000 blocks. Then the amount of new bitcoins created with each block gets cut in half. It continues to get cut in half every 210,000 blocks.
210,000 blocks at a rate of 1 block every 10 minutes is approximately 4 years.
This means that HALF of all the bitcoins that will ever exist were created in the first 4 years. Then half of the remaining bitcoins that will ever exist (one-fourth of ALL bitcoins) were created in the next 4 years. At that point, three-fourths (one-half + one-fourth) of all bitcoins had been created. Then half of the remaining bitcoins (one-eighth of ALL bitcoins) will be created in the following 4 years (we are currently about 25% of the way through that right now). This continues creating ever smaller amounts of new bitcoins every 4 years until somewhere around the year 2136 when each block will create 0.00000001 new bitcoins. After that the amount is reduced to 0 new bitcoins from then on.
So, in the year 2020 when it is cut from 12.5 new bitcoins per block to 6.25 new bitcoins per block, seven-eighths of all bitcoins will already have been created. Then in the following four years, one-sixteenth of all bitcoins (half of the remaining eight) will be created, leaving only one-sixteenth left not yet created.
why has it been so "easy" ?
The difficulty is adjusted to keep the global mining rate close to one block every 10 minutes. As more mining power is added to the system, blocks get created too quickly, so the protocol requires the difficulty to be increased. If global mining power ever decreases, blocks will get created too slowly, so the protocol requires the difficulty to be reduced in that case.
Specifically, the difficulty adjustment is made once every 2016 blocks. If it takes less than 20160 minutes to create those 2016 blocks, then the blocks are occurring too quickly. The difficulty is increased
proportionally to slow the rate back down to 10 minutes per block. If it takes more than 20160 minutes to create those 2016 blocks, then the blocks are occurring too slowly. The difficulty is decreased
proportionally to speed the rate back up to 10 minutes per block.
My understanding is that the miners are the ones that keep the blockchain alive. Now, that it will get harder and harder for them to mine, they will be less and less miners in the blockchain.
If the total global hash rate decreases, then it will get easier to mine.
If they will make income of just the transactions, wouldn't that make up for higher fees?
The subsidy of new bitcoins will get cut in half approximately every 4 years. Eventually, more of the miner's revenue will come from the transaction fees and less from the subsidy. This is how bitcoins was designed to operate. Eventually, all of the miner's revenue will some from the transaction fees.
If so, doesn't that go against the whole idea of having small fees, compare to what the current banks offer.
The Satoshi whitepaper said NOTHING about bitcoin having lower fees. Bitcoin was designed to eventually operate on a fee based system.
At the end of the day, crypto its a good investment or opportunity for people to make money
Bitcoin is intended to BE money. It is not intended to be an "investment opportunity for people to make money". Right now, because its popularity is growing and there is a high demand for owning bitcoins, the exchange rate is going up quickly. There will come a time though when the exchange rate will stabilize. At that time it will still be very useful for paying for things and storing value.
but when theres no money to be made, then what?
Then people will use it, just like they use any other form of money. They will have a job that will pay them with bitcoins. They will use bitcoins to pay for things. They will invest their bitcoins in businesses or loans.