Not everyone needs an instructor. Not everyone has the time or the money to spend on an instructor. Regardless of the reason, you can't have someone hold your hand every time you're on the course. You're going to have to learn to play and improve without an instructor if you're really going to get better.
There's no denying the benefits of being shown how to do something the right way. But just imagine if you needed the person who trained you at your job every day, or your driving instructor every time you got behind the wheel. If you wouldn't do that for those things, why would you do it for golf?
Research
No golf instructor was born with all their knowledge and wisdom. They had to learn sometime just like you. Luckily for you, nowadays you have the power of the internet at your fingertips. If you have a question about something, don't pay money or waste your time by meeting up with an instructor, just Google it.
There are thousands of articles and videos that will show you how to fix any problem that you might have. There's no excuse why you can't do your own research and figure out things for yourself. Whether it's a sea of videos or articles giving you tips, there are resources out there that you can use for free.
Practice
This one is obvious, right? Get out there and use everything you just learned from your research and apply it to your game. You don't need someone standing over your shoulder for every putt. Everyone gets better from trial and error.
You don't even need to be on a course to practice. Practice your putting in your house or your backyard. I liken this back to basketball. How often do you see basketball players shooting by themselves on the court? There's no reason why golfers can't work on different parts of the game wherever possible.
Make Some Friends
With all the time you're putting in on the course, you should be able to make a couple of friends. Once you do that, you all can help each other with your individual games. No need to pay someone to show you how to do something when you have a couple other people to help you for free.
Multiple heads are better than one, and great feedback from other golfers is a great tool to help you get better.
Golf With Players Better Than You
Nothing helps elevate your game quite like playing with better players. You'll never get much better if you aren't challenging yourself and always playing down to your competition. That's why you need to golf with the best to be the best.
Yes this almost guarantees that you'll lose, but in the long run it's more than worth it. Just don't get too frustrated with yourself if you do lose. Even the best golfers in the world don't always win.
Golfing with more polished players can also help you learn by watching them play. Instructors and lessons can be helpful, but there's no substitute for actually getting out on the course and actually playing in the heat of competition.