if you buy a decent bike it will have quality components an be made of quality material. Of course that will cost ya.
anything under $750 is not quality
Mine cost $1,200 discounted from $1,500 in the states and still use it daily 20 years on. Its a Scott

Since then its had at least 8 chains 6 freewheels (7speed) on chain ring set one wheel respoked , two new wheels,

You brought a shit bike an ur buying shit parts.

I have replaced my chain once, replaced brake components once, replaced cables once ,a few sets of brake pads and more tires/tubes than i can remember over the years
Its been on dirt roads as often as paved roads in Thailand and Nepal

NO one can tell you how long a bike will last as there are to many variables.

My bike i used on my 18 month trip thru se asia in 1982,( India, Nepal, Sri Lanka, Thailand, Malaysia & java which included over the Annapurna circuit an Everest base camp) was a specialized stumpjumper. Only replaced the front wheel cause i hit a cow in India, but LOTS of tires and brake pads

Grasshopper Adventures offers some nice bike tours in the area. They are located about one block behind the old Walkabout location.

We were out from 8 AM till early evening (about 25 km if I recall correctly). We first biked down the Riverside to catch the ferry boat below the Naga Casino and then rode across two islands before catching the ferry back across to the mainland (a van took the bikes from there). We saw everything we expected to and learned a lot from our guide that we wouldn't have known about otherwise. A bit pricey for folks on a shoestring budget (somewhere around 30-35 dollars for each of us all in) but well worth it. I used to be a tour guide by the way, and I was impressed.