I have a question is it compulsory to write in your SOP that why are you applying to this country and what is your financial resource and what are the opportunities after completion of your course ????
No it's not. Considering there are many aspect for leaving one country to another, for whatever purpose. But try not to use much of negativity for it makes the reader think negative about you. Every information is relevant and since you have many to discuss, try to focus about one of them, putting some sentiments into it not just generic essay
I too agree with trilam. It is not a must to include why apply to a particular country. If you have a good reason in that respect, you can certainly mention that. However, you need to talk about the features of your college (or university) and how they are aligned with your goals and aspirations. Also, you generally do not talk about how you bare the costs... If you apply for a scholarship, then it is different :)