Are you positive this house is only 30 years old, 1979? Looks way older than what I'm used to seeing in my area.
It seams that post was an after thought, as it's under a floor joist (that's failing), not a beam. Another floor joist of 2 could probably be "sistered" on to it, but you would be best having someone look at it in person.
If I saw a 30 year old house with a problem like this, I wouldn't walk away, I'd run. Are you sure you don't mean 130? There is obviously a defect that would place that much load on a single joist and cause it to crush around the telepost. The method someone chose for a temporary repair is worse than poor. The post insn't sinking into the wood, the wood is collapsing around the post. This needs some serious evaluation by an inspector or an engineer. Certainly looks like something resulting from a termite problem.
If this is a 30 yeard old house, it's had a very, very hard life.
The junction box would dispute that age. It looks to be from the '30's 0r '40's. But the joist size seems to indicate a post WW ll aged house. They seem closer in size to today's dimensions then actual 2x12's. But it could be the camera angle.
There are water stains on the crushed joist. Are they all water stained? Is that the only joist with a support? How far away from the foundation wall is this post? Insect damage usually starts at the perimeter and works it's way into the house.
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