I have had a old specialized stumpjumper and every 3-4 bike rides i go on something brakes or goes loose.
You're not alone. I tend to cause bike components to break, fail or wear away prematurely. Also sometimes I have to apply thread glue into threads to prevent them from loosening. For example, my kickstand bolts unscrew unless I apply thread glue. My front fender bolt also has loosened, if it repeats I'll have to apply thread glue there as well.
Bicycles are not like cars. Bicycles are vehicles that are made as light as possible. If it doesn't fail, it's too heavy. Make it lighter! In contrast to cars whose brake pads last for ages, I need to change my brake pads after 2000 km.
in the past year and a half i have gone through 2 rear derailleur's and the one im on now is on its way out after a crash
You didn't specify why you had to change the two rear derailleurs, but if you crash, you are expected to break components such as rear derailleurs.
What's more worrying that in today's high tech aluminum and carbon fiber components, it's possible that a component weakens invisibly due to a crash and subsequently fails. For example in road bikes where handlebars are wrapped with bar tape, you can't inspect an aluminum handlebar for beginning cracks after a crash reasonably unless you re-wrap the bars. For carbon fiber, the inspection would reveal nothing: it could be broken invisibly, and subsequently fail just riding along with no warning.
Bike chains don't last, especially MTB chains as they tend to become dirty. If you look after your chain well and ride on roads, 4000 km max is what you can get out of today's chains. For MTB, even 1000 km would be lucky. If you don't replace it in that 1000 km, it'll first wear away your sprockets, destroying them, maybe destroy your chainrings, and finally break in half.
1 front derailer
What is the failure mode? These usually don't fail, but then again if something doesn't fail, it's too heavy and needs to be made lighterweight. So I wouldn't be surprised if the derailleur manufacturing was experimenting with lighter-than-usual materials and constructions. Or maybe you shifter forcefully, thinking it would be a good idea to do a front shift forcefully?
Fortunately, today MTBs without front derailleur are available easily. Even so easily it might be hard to find a quality product with a front derailleur.
i have had about 7-8 inner tubes burst/puncture
I have to say I win. My puncture count probably exceeds 10.
i have had to replace the brake pads
On my road bike, brake pads wear after 2000 km of road riding. For MTB, where you need to brake practically all the time, I would assume 500 km max.
i have bent both steel pedals
Maybe considering a more expensive pedal made of better quality steel would help.
i have bent the crank
Cranks fail. Often.
my shifter literally fell into 3 pieces during a ride
Today it's trendy to use plastic trigger / STI shifters. Maybe an old-fashioned thumb / bar-end / downtube shifter would be more durable.
also the weld between the top tube and head tube had a crack
That's usual. Frames fail. If it doesn't fail, it's too heavy.
So my question is how can i continue riding and enjoying the sport on a budget?
You can't fully and easily. Durable components like steel handlebars are rare. However, choosing every component of your bike individually and selecting the best durability component for that application might help. You don't even need to do it all at once. For example, if an aluminum or carbon fiber handlebar fails, you can try to find if you still can find steel handlebars. Butted chromoly steel frames fortunately can still be found from many manufacturers. If your frame breaks again, don't weld, throw it away and buy a steel frame to replace it.