In my opinion, your original question that you state at the beginning starts out great, but then you water it down by adding things like "or something" and then conclude by asking if it's "a good idea".
Never ask "is X a good idea" on a StackExchange site. This is always a matter of personal opinion and your question will be closed.
Your question should almost always start with "What" or "How". You can then explain exactly the criteria of what you're looking for if you want to make your question longer; you can also tell us what you've already tried in your attempts to solve the problem yourself.
Questions that start with "Why" or in any way are asking for opinions, can easily be closed. Not all questions of this form are closed, but you really have to know what you are doing in order to ask this type of question. Therefore, to minimize the risk of your question being downvoted/closed, you should avoid asking questions that solicit opinions until you have a firm footing on the site.
I'd rewrite your question as follows. Note that this may still be considered to be an X/Y problem: someone may disagree with you that measuring your daily disk write amount is a useful way of determining how quickly you'll kill your SSD. However, that is an argument over a technical point, and they could probably answer your question by telling you that they disagree with this premise, and then suggest what you can do instead.
At least it wouldn't be closed as off-topic or opinion-based, after rewriting it as below.
Some general guidelines to consider:
When you are looking to accomplish some task using software, ALWAYS state the exact operating system and version you are using. Even if this information is not strictly required for the question to be answered, it is still helpful for the answerers to understand what kind of environment you're running on.
Be self-aware of what you are asking. Re-read your question several times, and look for anything that you could possibly have a reason to doubt. For example, are you 100% positive that your methodology will help you reliably determine how long your SSD will last? If you are not sure, you should revise your question: rather than assuming something that you are not sure of, you should ask the more general question that would resolve your doubt there. It is much harder to write a good answer to a question if it contains false statements or unsubstantiated claims. By only stating what you are sure of, and asking in your question what you are not sure of, you minimize the risk of being told you are suffering from the X/Y problem.
Keep working on your English. I know it is not your native language and you are trying, but keep trying. :) You will get better!
Title: How can I measure how much data I write daily?
I would like to run a few experiments and see how much data is being written on my disk when I perform specific tasks (e.g., programming, running virtual machines, working with databases, audio editing etc.).
I believe that measuring my usage on a day to day basis will be helpful, because I can remember what I did during that day, so if I observe my disk writes on a daily basis, I can reflect on what I might have done during that day that took so little (or so many) bytes written. I can then consider the expected MTBF bytes written of the SSD as stated by the manufacturer, and compare that to how many bytes I write per day based on which activities I perform, and calculate an estimate for how many days my SSD will last before it would, on average, probably start to fail.
I want to use that data to estimate SSD lifespan and decide how big of an SSD I really need to avoid killing the SSD in 1 year, since larger SSDs can level out the write wear across more NAND cells, so they tend to last longer. I have read somewhere that the average user writes 20 GB/day and that value may be used to estimate SSD lifespan, however I am probably not an average user. My usage may be much less or dramatically more than this; that is part of the reason I want to measure this value.
How can I gather this data on Windows INSERT VERSION HERE?