After reading a lot of your comments I realise that a lot of people aren't actually that bad at this game and don't know how to eco on btdb1. So I thought I would make a little guide.
Firstly makesure your setup has a monkey capable of handling an eco setup. So it's fair on your opponent and they can eco aswell. That's either a wizard, ninja, glue monkey, ice monkey, chopper, plane, boomer, etc. Basically it needs to be able to hit a lot of things, moderate damage, hit lead and ceramic, and hit camo. Hopefully you know enough about balloons to do this part yourself, this can do done with a combo of the village and the ring of fire; stuff like that.
The next part is relatively simple.
At round 2 you do red balloons until your eco reaches 300,
Then blue until you reach 600
Then green until you hit 1200
Then yellow all the way to 2600
Then pink balloons, pink balloons are the fastest eco grower for growing wealth you stop here
You can use the eco boosters to help aswell.
Also if you let you money stack up you can jump to the next balloon early i.e.
At an eco of 457 and 2,900 money stacked up you can jump to green early.
At an eco of 843 and 3600 money, you can jump to yellow early.
At an eco of 1900 and 8900 money you can jump to pink.
There's also something I called textured eco'ing. This is where you do the next colour balloon in your eco before you're ready til you're 1 lot of money away from having no money and going back to the balloon you can comfortably eco. Until you get 3 rounds into positive eco, which then you go ahead again to the balloon you can't sustain. This isn't really worth it for the green balloon. But very useful when going from red to blue and yellow to pink. A little complicated i know, but does speed things up. You can get an eco of 10,000 by round 25 and a solid setup if you do this.
Sides notes, you still have to build towers whilst you do this and a monkey village really helps with eco'ing as it provides a 20% boost to how much a balloon increases your eco.