That's a good start when you aren't comfortable enough in life. I think $10 a week is very affordable. Consider it a long-term investment, maybe over 20 years if possible, as you never know how much it will grow during that time. We do spend on our personal wants, so I believe we can minimize expenses and redirect that money into investing in Bitcoin.
Starting with $10 per week does not mean you must remain at that level for 20 years. That is an anomaly as we all aspire to grow in finances. Besides, it is at the current price of Bitcoin, $10 per week will really require so much time to realize a life-changing portfolio as I do not see Bitcoin doing X1000 easily. Therefore, to start with $10 per week requires that plans should also be in place to increase the inflow so that it will become easier to get 1 BTC which I consider something reason to hold for the future.
Based on my calculations, if you stick with $20 a week, you would end up investing $20,857 in 20 years. However, the value you'll be holding at that time is likely to be higher than that. So, if you were to get a 10x return on your initial investment, that's $200,000, which I think is a good outcome compared to not having that money at all. The $20 was just a sample amount, though. You can always go higher, take on more risk, perhaps invest $100 per week or more. Since we can make our own calculations and predictions, our target should be something that we find fulfilling.
You have said well but any amount is suitable for investing as long its what you can afford from your income. Its not advisable to take higher positions or risk the money you cant afford to lose. Stick to a plan and maintain consistency. Most issues beginners have is trying to cover the transactions fees for the little amount of Bitcoin every week when they plan to invest perhaps using DCA strategy. There is an alternative you could commit yourself to save the total money you will used to buy every week and do a larger buy once a month it could benefit you due to fees. Note you have to discipline yourself so you wont at any point fail to invest the right amount you budgeted. On the other hand, investing $100 every week is a great way to build up your Bitcoin holdings quickly if that's what you can afford.