ACE COMBAT 7: SKIES UNKNOWN

Simple enough to get this one:
Through normal gameplay (single or multiplayer) you will acquire MRP to spend on both parts and aircraft in the store. Certain aircraft are quite expensive, such as the Wyvern which is 2,000,000 MRP. However, the good news is that the lower-cost aircraft are worth as much as the Wyvern for this achievement. If you want to go through the money-making process fast, multiplayer is a good option, as even though you may not make as much MRP per match as you would per one single-player mission, you can complete multiplayer matches much faster. Once you have a good stockpile in your war chest, head over to the aircraft tree and start buying planes! You'll get the achievement shortly after purchasing the last one (starting planes already count, though I'm not certain if DLC-acquired planes do).