The first million you ever make is the hardest – or so the saying goes.
This is not only true, but its true at any scale. The first £100 you make, is the hardest. The first £1000 you make is the hardest. The first £10k you make is the hardest.
This is because the hard thing is not generating the money, but learning how to operate at a different order of magnitude. Earning £10k (or £20k or £30k) means getting an employer, turning up for work. Earning £100k means working at a higher level, customer interactions, or management or something. Earning £1m probably means running your own business (or winning the lottery). Each level requires totally different skills to the level below. The hard thing is learning the skills or knowledge necessary to switch levels.
It applies to anything else too. For example sports; competing nationally is a step up from competing locally, just as competing internationally is a step harder that competing nationally. They require different commitment levels, different fitness training regimes, different dietary plans.
What do you do in your life that you could do an order of magnitude better? What do you need to learn, what skills do you need to develop, in order to operate at that level?