Or, take a leap of faith and score a tent and light set up first. I have run many small tent for folks and I guarantee it will work.
I think you are suffering from lack of equipment. Not enough light, they just grow a super long stalk and dump over. By the time its three weeks old or so, it should be 2 or 3 inches tall and leaves should be at or past the diameter of the cup. As others have said, adding dirt is something when you are up potting or clones maybe, but you cant just keep burying the stalk.
With light and tent, proper amount of light will prevent that stalk just getting taller and taller. They will stay shorter and the leaves will grow wider and wider. By 4 or 5 weeks you will have a big ball of green leaves and its time to up pot to 5 gal, or what ever size you are going to use.
If you want to grow, get the light and tent first. One of my earliest indoor grows, I didnt have a tent, they were not a thing yet, so I hung the light in the open basement with the plant under it. The tent will concentrate and reflect available light around, plus temp and humidity can be maintained, pests out, etc., but it can be done without a tent. Wait until Mars Hydro has a sale, use discount code, 3x3 or 2x4 tents are very reasonable.
It will work.
Bubba
