Motorcycles are desirable, so a lot of people dream about owning and riding one. But, as with many things in life, if you can just barely afford the initial purchase, it can be difficult to afford to operate.
For example, if you could just barely afford either a car or motorcycle, but could not afford to insure it, would that be a good time in life to be operating that vehicle? Ongoing costs musts be a part of the cost of ownership, in terms of what you can afford.
Most folks look at purchase price, insurance, and gas for motorcycles. I did the same. At a time, I didn't know better. Those on here who speak from experience are trying to share with you the other things that need to be factored into your costs.
In the same way you need insurance because it costs you a lot if you either get tickets or if you get in a wreck without it, riding training is inexpensive compared to A) the cost of even a single avoidable accident and B) the cost of a ticket for not having an endorsement.
The MSF class does teach the basics. You mentioned you don't want bad habits, but teaching yourself to ride is an easy way to get those bad habits ingrained. Additionally, MSF doesn't just teach you how to operate the bike. They'll teach you how to see possible dangers and avoid them. That way, even if someone else is doing something crazy, like not stopping or driving diagonally, you'll have the training to anticipate this, see it happening, and react in a calm and controlled manner.
The road out there is filled with people who, by accident or ignorance, will do something that puts you at risk. MSF training is an affordable way to benefit from others' experience and learn about how/why/where this can happen and how to keep yourself out of it.
So, in the end, it's experience that says, 'You'll be better off if you take the MSF course, in both the short and long run, and it's so important that it should be factored into cost of ownership, not considered a luxury to do later'.
Never ride faster than you can stop