What I do like doing is buying apartment buildings near land value as a way to speculate on land while making an income. 

At about year 15 or 20 years experience he became a successful developer in Reno NV, building luxury homes in his own 20-lot subdivision.Personally, I get excited reading about young people who start out small with the BRRRR method, like Austin and William here:@Austin Fruechting @William Collinshttps://www.biggerpockets.com/forums/48/topics/429980-officially-financially-free-at-32----exciting-dayhttps://www.biggerpockets.com/forums/223/topics/445367-full-time-employee-multiple-brrrr-side-hustle-2875-to-goalAt 2.5 years' into investing, couldn't either of them buy a vacant lot and finance construction of a "speculative" home for sale?

It is also because you are not an investor, you are a speculator. 

Don't speculate whether market is going up or down.

Which sort of brings of the speculation bubble that may or may not be forming as a consequence.

Then it becomes speculating instead of investing.

 $40K for the down payment and another $80K for rehab.Now, there may be a speculative element here, too.  

If your not cashflowing then you're simply speculating.

Although the stock market can be pretty speculative, Real Estate Investment Trusts (REITs) are a way to get involved in additional real estate investing without necessitating additional loans and down payments, of course it is important to save up enough to buy in a lump sum that keeps your cost basis low even with the addition of a commission. 

Competition among hedge funds and 'big money' speculator buyers.