user2266: I'm just learning/getting started with bitcoin and one thing that's obvious straight away, is that the more computational power you can throw at it (with the cheapest energy possible), the more coins you can make.
Lots of people mining coins (myself included) just appear to be hobbyists - maybe with some nice equipment, but nonetheless, not 'industrial-scale'.
So why aren't there companies investing millions in solar panels and ACIS machines to mine bitcoins? Wouldn't someone that invested a few million (or more) in a setup like that monopolize bitcoin, in a manner of speaking? (Until people investing equally large amounts?). It'd raise the difficulty beyond what hobbyists could afford to make BTC profitable for them to mine. 
Maybe millions isn't enough, what if someone spent BILLIONS doing this? Would it have the effect I suspect?

user4842: Digging for gold was not a business in the early days, it was left to lunatics. Only later mining companies were started. 
The previous answers about the difficulty and upper limits in profits are good, but one should not forget how volatile bitcoin is. Most business owners wish to minimize risk to protect their capital. Mining bitcoins with serious capital should be considered extremely risky which very few sane people are willing to endeavor today.

user5875: The Bitcoin network automatically adjusts "difficulty" to produce a block every 10 minutes on average. As the difficulty rises it takes many more hashing attempts to find a block, so no matter how many exaflops in the network (we are already over 1) the number of coins will still be around 3600 daily (until the reward halves again.)
The only advantage to scaling is if you can scale faster and cheaper than the other miners, and even they you will only see an earning advantage until the difficulty changes and/or the competition steps up and matches their increase.
Technical Explaination of the mechanism:
https://en.bitcoin.it/wiki/Difficulty
More detailed and descriptive link for newcomers:
http://coin.furuknap.net/understanding-bitcoin-mining-difficulty/

user153: The proceeds of mining are the 3,600 BTC daily (at current levels, which will drop to 1,800 BTC per-day in late 2016).  All miners combined, no matter how many exist, are competing for these 3,600 BTC. 
This sets an upper limit to how much mining can occur at a profit.
If someone wishes to expand by putting "billions" into mining going beyond the equilibrium where mining is no longer profitable, they will certainly displace others.  But it is not economically prudent.

2266: <p>I'm just learning/getting started with bitcoin and one thing that's obvious straight away, is that the more computational power you can throw at it (with the cheapest energy possible), the more coins you can make.</p>

<p>Lots of people mining coins (myself included) just appear to be hobbyists - maybe with some nice equipment, but nonetheless, not 'industrial-scale'.</p>

<p>So why aren't there companies investing millions in solar panels and ACIS machines to mine bitcoins? Wouldn't someone that invested a few million (or more) in a setup like that <em>monopolize</em> bitcoin, in a manner of speaking? (Until people investing equally large amounts?). It'd raise the difficulty beyond what hobbyists could afford to make BTC profitable for them to mine. </p>

<p>Maybe millions isn't enough, what if someone spent BILLIONS doing this? Would it have the effect I suspect?</p>
 4842: <p>Digging for gold was not a business in the early days, it was left to lunatics. Only later mining companies were started. </p>

<p>The previous answers about the difficulty and upper limits in profits are good, but one should not forget how volatile bitcoin is. Most business owners wish to minimize risk to protect their capital. Mining bitcoins with serious capital should be considered extremely risky which very few sane people are willing to endeavor today.</p>
 5875: <p>The Bitcoin network automatically adjusts "difficulty" to produce a block every 10 minutes on average. As the difficulty rises it takes many more hashing attempts to find a block, so no matter how many exaflops in the network (we are already over 1) the number of coins will still be around 3600 daily (until the reward halves again.)</p>

<p>The only advantage to scaling is if you can scale faster and cheaper than the other miners, and even they you will only see an earning advantage until the difficulty changes and/or the competition steps up and matches their increase.</p>

<p>Technical Explaination of the mechanism:
<a href="https://en.bitcoin.it/wiki/Difficulty" rel="nofollow">https://en.bitcoin.it/wiki/Difficulty</a></p>

<p>More detailed and descriptive link for newcomers:
<a href="http://coin.furuknap.net/understanding-bitcoin-mining-difficulty/" rel="nofollow">http://coin.furuknap.net/understanding-bitcoin-mining-difficulty/</a></p>
 153: <p>The proceeds of mining are the 3,600 BTC daily (at current levels, which will drop to 1,800 BTC per-day in late 2016).  All miners combined, no matter how many exist, are competing for these 3,600 BTC. </p>

<p>This sets an upper limit to how much mining can occur at a profit.</p>

<p>If someone wishes to expand by putting "billions" into mining going beyond the equilibrium where mining is no longer profitable, they will certainly displace others.  But it is not economically prudent.</p>
